High Pressure Brings Warm Days and Cold Nights
High pressure dominating the UK is causing above-average temperatures and spring sunshine to persist over the coming days.
While England and Wales experienced their temperature peak on Wednesday, Thursday marked the warmest day of the year so far for Scotland and Northern Ireland, with Friday potentially exceeding that.
However, the clear skies responsible for the sunshine and warm daytime conditions also lead to significant overnight temperature drops.
Several locations in the Midlands and southern England saw a day-to-night temperature difference of approximately 216C following Wednesday's warmth, waking to frost on Thursday morning. Similar frosty conditions are expected for Friday and Saturday mornings.
It was a frosty start this week in Cropwell Bishop, Nottinghamshire
What Causes Large Temperature Swings Between Day and Night?
Wednesday was the warmest day of the year so far in many parts of England and Wales, but temperatures fell overnight, resulting in frosty mornings in some areas.
From Wednesday afternoon into early Thursday, parts of the Midlands and central southern England experienced a temperature range of about 216C.
For example, South Newington in Oxfordshire reached 196C during the day but dropped to -2.46C overnight. Similarly, Woburn in Bedfordshire rose to 19.46C before falling to -1.66C.
These large fluctuations are known as the diurnal temperature range, which is the difference between the highest and lowest temperatures recorded in a day.
Typically, afternoons are the warmest part of the day because the sun has had time to heat the ground and surrounding air, while dawn is usually the coldest time as the ground loses heat overnight.
UK temperature reaches 216C in warmest day of year so far
Why Are Temperature Swings So Pronounced in Early Spring?
March often brings a mix of warm sunny days and chilly, frosty mornings.
The UK experiences some of its largest diurnal temperature ranges in early spring due to several factors.
By March and April, the sun is higher in the sky and days are lengthening, delivering more energy more efficiently. However, after the long winter, the ground and lower atmosphere remain cold, allowing rapid cooling overnight.
Clear skies under spring high-pressure systems can intensify this contrast.
At night, heat escapes quickly and until the spring equilux, nights remain longer than days, leading to cold mornings.
During the day, the rising sun and clear skies enable rapid warming as the sun is more directly overhead, resulting in warm afternoons.
Dry air heats and cools faster than humid air, further widening the temperature gap.
These factors combine to increase the diurnal temperature range during early spring, especially during settled, sunny spells with light winds.
Other Factors Influencing the Diurnal Temperature Range
Solar radiation ultimately determines these temperature swings.
The strength and duration of direct sunshine vary, with sunnier, longer days providing greater warming potential than cloudy, dull days.
Air, land, and sea absorb and release heat at different rates, with land reacting more quickly than the sea. Consequently, temperature ranges tend to be greater inland, away from the coast.
Hillier areas also experience larger temperature swings. Humidity plays a significant role as moist, cloudy air slows both heating and cooling because water vapor absorbs heat.
Local geography affects heat storage in different surfaces, impacting temperatures during both day and night.
Should You Still Take Your Big Coat?
Due to the temperature fluctuations typical in March, it is advisable to assess the forecast daily.
Consult BBC Weather online or via the app for the latest updates in your area to determine whether a heavy coat or lighter clothing is appropriate.
