Friday 6th March
Thursday was the warmest day since 6th October with a maximum of 16.8C at 14.15. This high was due to welcome sunshine although thin cloud edging in from the west limited any further rise in the afternoon. The peak was 6C above my long-term average. The minimum of 5.8C was logged at 07.24 early Friday being 3.2C above average.
Friday arrived with total cloud cover, such a contrast with Thursday. A weather front will cross the UK today that will result in the cloud thickening further and possible light rain or drizzle from around mid-afternoon. A wind chill is a factor in the weather this morning. At 09.30 the air temperature was 6.6C whilst the brisk northerly breeze meant it felt more like 5.2C outside.
The wind has swung into the north today and will veer further into the northeast on Saturday and likely east on Sunday. This will result in lower temperatures than of late under cloudy skies. A large area of rain is currently crossing the English Channel, drifting northwards, arriving here mid-afternoon.
Last month I highlighted the minimal diurnal temperature range on several days, the difference between the maximum and minimum temperature over a twenty-four hour period. Often in February it was just 2C or 3C due to the persistent cloud cover limiting any sunshine and minimising the loss of warmth into the atmosphere overnight. The past twenty-four hours has seen a much greater diurnal range of 11.0C. Below is a more more detailed coverage of this meteorological feature
What influences the size of the daily temperature range
Several factors determine how large or small the diurnal temperature range is on any given day. At the heart of it is solar radiation: the strength and duration of sunlight directly influence the daytime maximum. Longer, sunnier days lead to stronger heating, while dull, overcast days limit how high temperatures can climb.
Humidity plays a major role too. Moist air slows both heating and cooling because water vapour retains heat. As a result, humid days often have smaller temperature ranges, whereas dry air allows for quicker warming during the day and more rapid cooling overnight. Cloud cover has a similar effect. Clouds reflect some of the Sun’s energy during the day and act as a blanket at night, keeping temperatures from falling as far. On cloudy days and nights, the temperature range is typically narrower than on clear ones.
Local geography also matters. Different surfaces store heat in different ways, which can impact both daytime and nighttime temperatures.
Why diurnal temperature range matters
Tracking diurnal temperature range helps meteorologists understand how weather conditions are developing across the UK. Large swings between daytime and nighttime temperatures indicate clear skies, dry air and high levels of radiative cooling, conditions that can lead to overnight frost even after a mild afternoon. Smaller ranges suggest cloudier, more humid conditions, often associated with milder nights but cooler days.
Beyond weather forecasting, DTR plays a role in several areas of science and daily life. In agriculture, it influences crop development, particularly in fruit-growing regions where warm days and cool nights can improve sugar accumulation and flavour. In climate science, long-term changes in DTR help researchers understand how the atmosphere is warming.
Understanding diurnal temperature range is also important for public health. Large temperature swings can pose challenges for vulnerable groups, particularly during early spring when cold nights can follow relatively mild days.