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This section looks at the different climates in each
region of the UK. The notes below highlight the importance
of local features in producing subtle variations.
3.1 England
Temperature – over England the mean annual
temperature at low altitudes varies from 8.5 °C to
11 °C, with the highest values occurring around or
near the coast of Cornwall. The mean annual temperature
decreases by approximately 0.5 °C for each 100 metres
increase in height so that for example, Great Dun
Fell in Cumbria (at 857 m) has an annual mean temperature
of 4 °C.
Winter temperatures in the British Isles are influenced
by the thermal characteristics of the surrounding
sea. They reach their lowest values in February or
early March, so in coastal areas, February is normally
the coldest month. Inland, away from the influence
of the sea, the coldest period occurs a little earlier
and January and February are the coldest months. Indeed,
it was in an inland valley that the lowest temperature
recorded in England was made — at Newport in Shropshire
on 10 January 1982, -26.1 °C. As a comparison, the
coldest temperature ever recorded in Plymouth in Devon
was –8.8 °C on 2 January 1979.
July is normally the warmest month in England. Again,
the extreme temperatures occur inland, away from the
influence of the sea. The UK record temperature of
37.1 °C at Cheltenham on 3 August 1990, was
beaten by a number of stations on 10 August 2003,
with Brogdale near Faversham in Kent, reporting the
highest at 38.5 °C.
Precipitation
Rainfall
 |
Fig
1: Monthly averages
(1961–90) of rainfall (mm) for a selection of
stations in England. |
The Lake District is the wettest part of England,
with annual totals exceeding 2,000 mm, comparable
to the Highlands of Scotland. The Pennines and the
moors of south-west England are almost as wet. Conversely,
all of East Anglia and much of the Midlands, eastern
and north-eastern England, as well as parts of the
south-east experience less than 700 mm in a year.
The typical occurrence for rain is about one day
in three in England, especially in winter, rather
than in summer, although in most years, there are
likely to be long dry spells.
Near the south coast there is an appreciable summer
minimum and winter maximum of rainfall, with totals
in July about half those in January. The western,
northern and eastern coasts are likely to see the
driest month in spring and the wettest month in late
autumn. It can be a different situation in inland
areas, with parts of the Midlands experiencing a summer
rainfall maximum. This reflects the higher frequency
of thunderstorms (convectional rain) in the more central
and south-eastern parts of England. For example thunder
occurs on average 15 days per year in London and Birmingham,
but in the west and north-west the frequency declines
to around eight days per year.
The maximum rainfall recorded in one day was 279
mm at Martinstown (Dorset) on 18 July 1955.
Snow
 |
Fig 2: 30-year (1961–90)
average number of days in month with snow lying
at 0900 hours at selected stations. |
Snow is comparatively rare near sea level in England,
but is much more frequent over hills. The average
number of days each year when sleet or snow falls
in England varies from about 10 or less in some south-western
coastal areas to over 50 in the Pennines. Snow rarely
lies on the ground at sea level before December or
after March and the average number of days with snow
lying in England varies from five or less around the
coasts to over 90 in parts of the Pennines.
The number of days of snowfall and snow cover varies
enormously from year to year. At many places in England
in the last 50 years, it has ranged from none at all
in a number of winters, to in excess of 30 days during
the winters of 1946/47 and 1962/63. Even places near
the coast experienced prolonged snow cover during
these two winters, especially over higher ground,
resulting in severe disruption to transport. Fortunately,
such prolonged spells of winter snowfalls are comparatively
rare.
Wind
 |
Fig 3: Monthly average
number of days (1961–90) with gales at selected
stations. |
The strongest winds in the United Kingdom are associated
with the passage of deep depressions across or close
to the British Isles. These are most frequent during
winter, when the depressions are most active over
the open ocean. The western coasts are most exposed
to the stronger winds at low altitudes, with Ireland
affording protection to much of England. The most
exposed areas are the coasts of Devon and Cornwall
where there are about 15 days of gale a year. Inland
the number of days of gale decreases to fewer than
five days a year.
The highest gust recorded at a low-level site, was
103 knots (118 m.p.h.) at Gwennap Head, Cornwall,
on 15 December 1979.
Sunshine
 |
Fig 4: 30-year (1961–90)
average monthly duration of bright sunshine in
hours for selected stations. |
On sunny days in summer, the formation of convective
(cumulus) cloud takes place over land, whilst skies
over the sea remain cloud-free. Therefore, the sunniest
parts of England (and the whole of the British Isles)
are along the south coast of England. Many places
along this coast achieve annual average figures of
around 1,750 hours of sunshine. The maximum duration
in one month of bright sunshine is 383.9 hours at
Eastbourne, East Sussex, in July 1911.
The dullest parts of England are the mountainous
areas with annual average totals of less than 1,000
hours. The minimum duration in a month, was zero hours,
recorded at Westminster, Greater London, December
1890.
Visibility – many parts of England, especially
those remote from industrial and urban areas, enjoy
good visibility. This is particularly true of most
coastal areas, the mountains and the moorlands.
Over high ground in England, hill fog can be both
extensive and frequent , and it is a potential hazard
to be borne in mind by walkers. Indeed, Great Dun
Fell (857 metres) in Cumbria had an average of 233
days of fog per year between 1963 and 1976.
3.2 Scotland
Temperature – over Scotland the mean annual
temperature at low altitude ranges from about 7 °C
in the Shetland Islands, in the far north, to 9 °C
on the coasts of Ayrshire and Dumfries and Galloway
in the south-west. Due to the environmental lapse
rate, there is a temperature decrease of about 0.6
°C for each 100 m rise in height, and as a result
the temperatures over higher ground are generally
colder. For example, Braemar (at 339 m above mean
sea level) has an annual mean temperature of 6.4 °C
while the corresponding value on Ben Nevis (altitude
1,344 m ) is 0.3 °C.
In common with other parts of the British Isles,
winter temperatures are influenced by the surrounding
areas of sea. The North Sea is cooler than the waters
off the west coast, so the east coast of Scotland
is generally cooler than the west coast. In general,
January and February are the coldest months when the
daytime maximum temperatures over low ground average
around 5–7 °C. On rare occasions in the lee of high
ground, a föhn effect can cause temperatures to reach
around 15 °C. The lowest temperatures occur inland
away from the moderating influence of the sea, and
in valleys into which cold air sinks. In these conditions,
the temperature dropped to –27.2 °C at Braemar on
10 January 1982 and more recently at Altnaharra on
30 December 1995. (This is the lowest temperature
ever recorded in the British Isles.) In coastal areas,
such cold nights are not experienced and as an example,
the lowest temperature recorded at Lerwick in the
Shetland Islands in the 30 years between 1961 and
1990 is only –9 °C.
In summer, the more northerly latitude of Scotland
explains the drop in the amount of solar radiation.
Thus, the temperatures in Scotland are on average
a few degrees cooler than in England. For example,
in July the average daily maximum temperature at Glasgow
is 19 °C compared with London 22 °C. July and August
are normally the warmest months in Scotland. As the
sea has a cooling influence on coastal areas, the
highest temperatures occur inland. The highest temperature
recorded in Scotland was 32.9 °C at Greycrook
(Scottish Borders) on 9 August 2003, beating the previous
Scottish record of 32.8 °C at Dumfries on 2 July
1908 and on several occasions at other places in the
19th century.
Precipitation
Rainfall
 |
Fig 5: Monthly averages
(1961–90) of rainfall (mm) for a selection of
stations in Scotland. |
There is a misconception that the whole of Scotland
experiences high rainfall. In fact, rainfall in Scotland
varies widely, with a distribution closely related
to the topography, ranging from over 3,000 mm per
year in the western Highlands (similar to the total
rainfall experienced in the mountains of the Lake
District in England and Snowdonia in Wales) to under
800 mm per year near the east coast (comparable with
the Midlands of England).
The frequency of thunderstorms in Scotland is around
three to nine days per year. This is relatively low
compared with an average of 9–15 days per year over
England. The number of thunderstorms can vary widely
from year to year, but in general the northern and
eastern coasts of Scotland average only three or four
days with thunder per year, whilst inland values range
from nine in the south to six in the north.
Snow
 |
Fig 6: 30-year (1961–90)
average number of days in month with snow lying
at 0900 hours at selected stations. |
Temperatures generally decrease with height, so precipitation
falling to the ground as rain at low-level sites may
fall as snow over higher ground. Consequently, there
is a marked increase with altitude in the number of
days with falling snow and also in the number of days
with snow lying on the ground.
The average number of days with sleet or snow falling
in Scotland ranges from 20 or less near the west coast
to over 100 days in the Cairngorm Mountains and some
other high peaks. Snow rarely lies on the ground at
sea level before November or after April. On low ground
in the Western Isles and in most coastal areas of
Scotland, snow lies on an average for less than 10
days per year, although this increases to around 15–25
days for coasts in the north and north-east. However,
over the mountains, snow typically lies for more than
50 days per year.
In heavy snow, there can be quite extensive drifting,
especially over higher ground. Snow deposited in natural
hollows, such as high-level corries, can persist for
some considerable time, an effect utilised to good
effect by the development of the skiing industry in
Scotland, and a few of these high level, north-facing,
snow beds are semi-permanent, only disappearing in
very occasional summers. On the highest summits, such
as Ben Nevis, snow cover typically persists for around
six or seven months of the year.
Winds
 |
Fig 7: Monthly average
number of days (1961–90) with gales in selected
stations. |
The most common direction from which the wind blows
in Scotland is from the south-west, but the wind direction
often changes markedly from day to day with the passage
of weather systems. There is a close relationship
between surface isobars and the wind speed and direction
over open, level terrain. However, in mountainous
areas local topography also has a significant effect,
with winds tending to blow along well defined valleys.
Since many major Atlantic depressions pass close
to or over Scotland, the frequency of strong winds
or gales is higher than in other parts of the British
Isles. Over low ground the windiest areas are the
Western Isles, the north-west coast and the Orkney
and Shetland Islands with over 30 days with gales
per year in some places.
Sunshine
 |
Fig 8: 30-year (1961–90)
average monthly duration of bright sunshine in
hours for selected stations. |
Generally, Scotland is more cloudy than England,
due mainly to the hilly nature of the terrain and
the proximity of low-pressure systems from the Atlantic.
Despite this, parts of Angus, Fife, the Lothians,
Ayrshire and Dumfries and Galloway average over 1,400
hours sunshine per year. This compares favourably
with coastal areas of Northern Ireland and the north
of England, but is less than the annual totals of
over 1,700 hours experienced along the south coast
of England. The dullest parts of Scotland are the
more mountainous areas, with an annual average of
less than 1,100 hours of sunshine over the mountains
of Highland Region. Mean daily sunshine figures reach
a maximum in May or June and are at their lowest in
December. Wind and cloud play their part but the key
factor is day length throughout the year due to the
relatively high latitude of Scotland.
Visibility – Scotland often enjoys excellent
visibility, largely because of its remoteness from
the industrial and urban areas of Britain and mainland
Europe. In the industrial areas of central Scotland
the switch away from coal fires and the decline in
traditional heavy industry has reduced the incidence
of smoke haze caused by local air pollution. However,
cloud with a very low base can often shroud high ground
with hill fog. Extensive hill fog often develops,
especially in the west, when a moisture-laden south-westerly
airstream covers the country. The resulting low visibility
and drizzle, can pose a hazard for hill walkers and
motorists.
Radiation fog may form overnight in low-lying inland
areas on clear, calm nights, particularly in winter.
Sea fog formed by advection cooling can develop over
the North Sea. Known locally as haar, it sometimes
ruins what would otherwise be a fine day on or near
the east coast, or in the Northern Isles, between
April and September. Both these types of fog tend
to break up and disperse during daytime, although
inland, during the winter, mist and fog does sometimes
persist. At Edinburgh, the midday visibility is less
than 1,000 m on 3% of December days.
3.3 Wales
Temperature – Over Wales, the mean annual
temperature at low altitude varies from about 9.5
°C to 10.5 °C, with higher values occurring around
or near the coasts. The mean annual temperature decreases
with the environmental lapse rate, by approximately
0.5 °C for each 100 m increase in height, so that
for example Bwlchgwyn, Wrexham, at 386 m, has an annual
mean temperature of 7.3 °C. On this basis, Snowdon
at 1,085 m would have an annual mean temperature of
about 5 °C.
In winter the coldest areas are away from the coasts,
where the sea has little influence on temperature.
Cold air drains into the floors of inland valleys,
and it is here that the lowest temperatures are found.
Indeed, it was under such conditions that the lowest
recorded temperature in Wales has been recorded, -23.3
°C at Rhyader on 21 January 1940.
Coastal areas do not experience such cold nights,
for example the lowest temperature recorded at Brawdy
in Pembrokeshire was –10.7 °C on 13 January 1987.
On the opposite extreme some of the highest winter
temperatures recorded in the British Isles have occurred
in Wales up to 18 °C. These occur when a powerful
föhn effect develops downwind of Snowdonia in a moist
south to south-easterly airflow.
July is normally the warmest month in Wales, with
the highest temperatures occurring away from the cooling
influence of the sea. The highest temperature recorded
in Wales was 35.2 °C at Hawarden Bridge in Flintshire
on 2 August 1990.
Precipitation
Rainfall
 |
Fig 9: Monthly averages
(1961–90) of rainfall (mm) for a selection of
stations in Wales. |
Rainfall in Wales varies widely, with the highest
average annual totals being recorded in the mountainous
areas of Snowdonia, with the wettest parts having
over 3,000 mm per year, and the Brecon Beacons, where
the yearly fall is comparable to the English Lake
District or the Western Highlands of Scotland. In
the east, close to the border with England, annual
totals are similar to those over much of the English
Midlands (around 1,000 mm per year), whilst similar
totals are also found in the coastal areas.
Throughout Wales, the months of October to January
are significantly wetter than those from February
to September, unlike places in south-east Scotland
and the English Midlands where July and August are
often the wettest months of the year. This is a reflection
of the relatively low frequency of thunderstorms in
Wales compared with England. For example at Cardiff,
thunder occurs on an average of 11 days a year, compared
with 15–20 in many places in England. In the west
and north-west, the frequency declines to around eight
days per year.
Snow
 |
Fig 10: 30-year (1961–90)
average number of days in month with snow lying
at 0900 hours at selected stations. |
Snow is comparatively rare near sea level in Wales
but much more frequent over the hills. The average
number of days each year when sleet or snow falls
in Wales varies from about 10 or less in some south-western
coastal areas to over 40 in Snowdonia. Snow rarely
lies on the ground near sea level before December
or after March, and the average number of days with
snow lying in Wales varies from six or less around
the coasts to over 30 in Snowdonia.
The number of days of snowfall and snow cover varies
enormously from year to year. At many places in the
last 50 years, it has ranged from none at all in several
winters, to in excess of 30 days during the Winters
of 1946/47 and 1962/63. Even places near the coast
experienced prolonged snow cover during these two
winters.
In heavy snowfalls there can be quite extensive drifting
of snow in strong winds, especially over higher ground,
resulting in severe dislocation of transport. Fortunately,
such occasions are rare, but one of the worst snowstorms
in the 20th century in South Wales occurred on 7 and
8 January 1982, when depths of one metre or more were
commonplace, with severe drifting and power lines
brought down.
Winds
 |
Fig 11: Monthly average
number of days (1961–90) with gales in selected
stations. |
The strongest winds in the British Isles are associated
with the passage of deep depressions across or close
to the country. These are most frequent in winter
and it is then that gales are most frequent. As these
depressions are most intense over the open Atlantic
Ocean, low-lying parts of Wales have more-frequent
gales. For example, in the extreme south-west of Dyfed
about 30 days of gales occur on average per year.
Further north, Wales is more protected by Ireland.
Other coastal areas have 15 days or more of gale with
the number of days decreasing to five days or fewer
inland.
In general, wind speed increases with height, with
strongest winds being observed over the summits of
hills and mountains. There are no wind recording stations
at high altitudes in Wales, so no data can be given
but, as an indication, Snaefell on the nearby Isle
of Man (at 615 metres) has, on average, over 200 days
of gales a year.
Sunshine
 |
Fig 12: 30-year (1961–90)
average monthly duration of bright sunshine in
hours for selected stations. |
Wales is generally cloudier than England as a result
of the hilly nature of the terrain that forces up
moist, maritime air moving in from the Atlantic. Even
so, the south-western coastal strip of Dyfed has an
annual average of over 1,700 hours of sunshine – a
total also achieved by many places on the south coast
of England. The dullest parts of Wales are the mountainous
areas, with average annual totals of less than 1,100
hours.
Mean daily sunshine figures reach a maximum in May
or June, and are at their lowest in December. The
key factor is the length of day throughout the year,
but prevailing winds and cloud play their part as
well.
Visibility - Much of Wales enjoys excellent
visibility. The traditional areas of heavy industry
are close to the southern coast – a location that
is, in itself, relatively breezy and free from serious
reductions of visibility by reason of smoke.
Fog statistics are scarce but, given the mountainous
nature of the country and the proximity to the sea,
hill fog can be both extensive and frequent and is
a potential hazard to be borne in mind by walkers
in Snowdonia and the Brecon Beacons.
3.4 Northern
Ireland
Temperature – over Northern Ireland the mean
annual temperature at low altitudes varies from about
8.5 °C to 9.5 °C with higher values occurring around
or near the coasts. The mean annual temperature decreases
by about 0.5 °C for each 100 metre increase in height
so that, for example, Parkmore Forest in County Antrim
(at 235 m) has an annual mean temperature of 7.4 °C.
On this basis, Slieve Donard, the Province’s highest
mountain (at 852 m) would have an annual mean temperature
of about 4.5 °C.
In winter, the temperatures of coastal areas are
influenced by the surface of the surrounding sea.
Inland, the lowest temperatures are to be found, where
cold air drains into the bottoms of valleys. The lowest
temperature recorded in Northern Ireland was –17.5
°C at Magherally, County Down, on 1 January 1979,
whilst in coastal areas the lowest recorded temperature
at Helens Bay during the 30-year period between 1961
and 1990 was -5.4 °C.
July is normally the warmest month in Northern Ireland,
and the highest temperatures of all have occurred
inland, furthest away from the cooling influence of
the Atlantic. The highest recorded temperature was
30.8 °C at Knockarevan, County Fermanagh, on 30 June
1976, and at Shaw’s Bridge, Belfast, on 12 July 1983.
Precipitation
Rainfall
 |
Fig 13: Monthly averages
(1961–90) of rainfall (mm) for a selection of
stations in Northern Ireland. |
Rainfall in Northern Ireland varies widely, with
the highest annual average totals being recorded in
the Sperrin, Antrim and Mourne Mountains where the
yearly fall of around 1,600 mm is about half that
of the English Lake District, or the western Highlands
of Scotland. In the east, close to the coast, and
near to the southern and eastern shores of Lough Neagh,
the annual totals of just under 800 mm are similar
to those near the Firth of Forth in Scotland. Generally,
rainfall distribution is closely related to topography.
The seasonal variation of rainfall in Northern Ireland
is not large, but throughout the province the wettest
months are between August and January, unlike places
in south-east Scotland or in the English Midlands,
where July and August are often the wettest months
of the year. This is partly a reflection of the relatively
low frequency of thunderstorms in Northern Ireland,
compared with that of England. For example, at Armagh
thunder occurs on an average of less than four days
per year, compared with 15–20 at many places in England.
Only in a few places, mainly away from the coasts,
does the frequency of thunder exceed five days per
year.
Snow
 |
Fig 14: 30-year (1961–90)
average number of days in month with snow lying
at 0900 hours at selected stations. |
Snow is comparatively rare near sea level in Northern
Ireland, but much more frequent over the hills. The
average number of days each year when sleet or snow
falls in Northern Ireland varies from around 10 near
the east coast to over 30 in the mountains of Sperrin,
Antrim and Mourne. Snow rarely lies on the ground
at sea level before December or after March and the
average annual number of days with snow lying in Northern
Ireland varies from less than five around the coasts
to over 30 in the mountains.
The number of days of snowfall and snow cover varies
enormously from year to year. At many places in the
last 50 years it has ranged from none at all in several
winters, to in excess of 30 days during the winters
of 1962/63 and 1981/82. Even places near the coast
experienced prolonged snow cover during these two
winters. With heavy snowfalls there can be quite extensive
drifting of the snow in strong winds, especially over
the higher ground, resulting in severe disruption
of transport. Fortunately, such occasions are comparatively
rare.
Winds
 |
Fig 15: Monthly average
number of days (1961–90) with gales in selected
stations. |
The strongest winds in the United Kingdom are associated
with the passage of deep depressions across or close
to the British Isles. These are most frequent during
winter, which is when gales can occur on exposed western
and northern coasts of both Britain and Ireland. For
example, the Hebrides experience on average about
35 days of gale a year, and the extreme south-west
of England about 30. In Northern Ireland, the coastal
areas are not so exposed as these areas are afforded
some protection both by the rest of Ireland and adjacent
parts of Scotland. Thus, the coastal areas of the
counties of Antrim and Down have about 15 days of
gale per year, while the number of days decreases
inland to five or fewer.
In general, wind speed increases with height, with
strongest winds being observed over the summits of
hills and mountains. There are no wind recording stations
at high altitudes in Northern Ireland, so no data
can be given but, as an indication however, Snaefell
on the nearby Isle of Man (at 615 metres) averages
over 200 days of gale a year.
Sunshine
 |
Fig 16: 30-year (1961–90)
average monthly duration of bright sunshine in
hours for selected stations. |
On the whole, Northern Ireland is cloudier than England
because of the hilly nature of the terrain and the
proximity to the Atlantic. Even so, the coastal strip
of County Down manages an annual average total of
over 1,400 hours of sunshine. This compares favourably
with many coastal areas of England and Wales, though
not with the 1,750 hours achieved in places along
the south coast of England. The dullest places in
Northern Ireland are the more-mountainous areas, where
the annual average falls below 1,100 hours.
Mean daily sunshine figures reach a maximum in May
or June, and are at their lowest in December.
Visibility – given Northern Ireland's peripheral
location, away from the industrial and urban areas
of Britain and Europe, much of the Province enjoys
excellent visibility. Any early morning mist or fog
that might develop will usually clear rapidly, though
it can be much more persistent during winter months.
Given the hilly nature of the country and its relative
proximity to the sea, hill fog can be both extensive
and frequent and is a potential hazard to be borne
in mind by walkers.
| 4.
Additional UK climate information |
UK climate information
1. Make a concise definition of the term climate.
2. What are the five main factors which influence
the climate of a locality?
3. What is the name given to the type of climate
which affects the British Isles?
4. Explain why Moscow, on a similar latitude to London,
has warmer summers and colder winters than the English
capital.
5. Explain the meaning of the term 'environmental
lapse rate'.
6. Outline the meaning of the following phrases:
a. orographic, or relief rain,
b. föhn effect,
c. rain shadow.
7. Explain the different mechanisms that produce
frontal and convective rain.
8. What is the correct value for the number of days
with snow falling over the Cairngorms – 40, 60, 80
or 100?
9. Which English weather records are held by Martinstown
in Dorset and Gwennap Head in Cornwall?
10. What is an urban heat island? What are the meteorological
conditions that may favour its formation?
11. Why do temperatures in the inland parts of the
UK differ from those localities that are nearer the
sea?
12. Describe and explain the type of weather hazards
which walkers might face in upland parts of the UK.
13. Outline the meteorological conditions by which
fog may develop in parts of the UK.
14. The highest recorded temperature in England was
made at Brogdale near Faversham in Kent:
a. Was it 36.5, 37.5,
38.5 or 39.5 °C?
b. In which year did this
occur 1990, 1995, 2000 or 2003?
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