British weather is divided into 4 seasons – Spring, Summer, Autumn and Winter.
Climatologically The Met Office classes the first day of spring as the 1st day of March, but because of the variation in the days on which the equinox and solstice falls, it is more convenient to use whole months. The Met Office therefore classifies the spring months as being March, April and May. Traditionally the first day of spring is Astronomically derived, and is March 20th. At the time of the equinox the Sun will cross directly over the Earth’s equator. This moment is known as the vernal equinox in the Northern Hemisphere. For the Southern Hemisphere, this is the moment of the autumnal equinox. Traditionally spring is thought to be about new beginnings, the weather gets warmer, the days get longer…..In spring, the axis of the Earth is increasing its tilt toward the Sun and the length of daylight rapidly increases for the relevant hemisphere. The hemisphere begins to warm significantly causing new plant growth to “spring forth,” giving the season its name. Spring is generally a calm, cool and dry season, particularly because the Atlantic has lost much of its heat throughout the autumn and winter. However, as the sun rises higher in the sky and the days get longer, temperatures can rise relatively high, but often tend to drop off again at night due to the cool oceans and the warm weather dependent solely on the sun. Thunderstorms and heavy showers can develop occasionally particularly towards the end of the season.
There is a fair chance of snow earlier in the season when temperatures are colder. Some of the country’s heaviest snowfalls of recent years have happened in the first half of March and snow showers can occur infrequently until mid-April.
Mean temperatures in Spring are markedly influenced by latitude. Most of Scotland and the mountains of Wales and northern England are the coolest areas of the UK, with average temperatures ranging from -0.6 to 5.8 °C (30.9 to 42.4 °F). The southern half of England experiences the warmest spring temperatures of between 8.8 and 10.3 °C (47.8 and 50.5 °F)
Summer lasts from June to September and is the warmest season. Rainfall totals can have a wide local variation due to localised thunderstorms. These thunderstorms mainly occur in southern, eastern, and central England and are less frequent and severe in the north and west. North Atlantic depressions are not as severe in summer but increase both in severity and frequency towards the end of the season. Summer can see high pressure systems from the Azores High.
Climatic differences at this time of year are more influenced by latitude and temperatures are highest in southern and central areas and lowest in the north. Generally, summer temperatures seldom go above 30 °C (86 °F), which happens more frequently in London and the South East than other parts of the country. Scotland and northern England have the coolest summers, while Wales and the south-west of England have warmer summers, and the south and south-east of England have the warmest summers.
Autumn in the United Kingdom lasts from October to November. The season is notorious for being unsettled—as cool polar air moves southwards following the sun, it meets the warm air of the tropics and produces an area of great disturbance along which the country lies. This combined with the warm ocean due to heating throughout the spring and summer, produces the unsettled weather of autumn. In addition, when the air is particularly cold temperatures on land may be colder than the ocean, resulting in significant amounts of condensation and clouds which bring rain to the country.
Atlantic depressions during this time can become intense and winds of hurricane force (greater than 74 mph) can be recorded. Western areas, being closest to the Atlantic, experience these severe conditions to a significantly greater extent than eastern areas. As such, autumn, particularly the latter part, is often the stormiest time of the year. One particularly intense depression was the Great Storm of 1987.
However, the United Kingdom sometimes experiences an ‘Indian Summer’, where temperatures particularly by night can be very mild and rarely fall below 10 °C (50 °F). Such events are aided by the surrounding Atlantic Ocean and seas being at their warmest, keeping the country in warm air, despite the relatively weak sun.
Winter in the UK lasts from December to February. The season is generally cool, wet and windy. Precipitation is plentiful throughout the season, though snow is relatively infrequent despite the country’s high latitude: The only areas with significant snowfall are the Scottish Highlands and the Pennines. Towards the later part of the season the weather usually stabilises with less wind, less precipitation and lower temperatures. This change is particularly pronounced near the coasts mainly because the Atlantic Ocean is often at its coldest during this time after being cooled throughout the autumn and the winter. The early part of winter however is often unsettled and stormy; often the wettest and windiest time of the year. Mean winter temperatures in the UK are most influenced by proximity to the sea. The coldest areas are the mountains of Wales and northern England, and inland areas of Scotland. In the 1990s and 2000s, most of the winters were milder and usually wetter than average with daytime temperatures going below freezing a rare occurrence. In fact, the winter of 1995/1996 was the only one which was defined as below average in terms of the UK as a whole. The winters of 2008/09, 2009/10 and 2010/11 have however seen a different pattern with these three winters being defined as below or well below average with large snowfall amounts widespread and very low temperatures; this was the first time three consecutive cold winters in the UK have occurred since the 1960s.
The climate of the United Kingdom has not always been the way it is today. During some periods it was much warmer and in others it was much colder. The last glacial period was a period of extreme cold weather that lasted for tens of thousands of years and ended about 10,000 years ago. During this period the temperature was so low that much of the surrounding ocean froze and a great ice sheet extended over all of the United Kingdom except the south of England. We think we are cold when temperatures reach 0, imagine being around back then!
The cold period from the 16th to the mid-19th centuries is known as the Little Ice Age.