The Met Office has confirmed that today is the hottest day of the year so far due to a lesser-known weather phenomenon. Temperatures reached 20.9C in Gogerddan, Wales, surpassing the previous record of 19.2C set on March 5 in London. London also experienced a high temperature of 20.2C today.

The national weather agency predicts a decrease in temperatures later tonight and into tomorrow morning, but most areas can expect a warm and sunny day tomorrow with temperatures reaching around 17C or 18C. The weekend is expected to be dry with sunny intervals for many regions, although there may be a chance of rain in northern Scotland on Saturday, spreading more widely in the north on Sunday, accompanied by cooler temperatures.

The high temperatures today are attributed to the Foehn effect, a weather phenomenon where moist air is pushed up one side of a mountain, cools down, and then warms up rapidly as it descends on the other side of the mountain. In the UK, this effect is most commonly observed in the Scottish Highlands, with wet weather on the west side of the mountains and warmer, sunnier conditions on the east side.

Looking ahead, the Met Office forecasts a potential drop in temperatures later in the month, with the possibility of snow in some areas. From March 22 to March 31, weather conditions are expected to be more changeable and unsettled in some regions as Atlantic frontal zones move across the UK. The north is likely to experience more active weather systems compared to the south, where a ridge of high pressure from the subtropical Atlantic may bring milder conditions.

Towards the end of March, there could be a brief cold spell with northerly winds, increasing the chance of snowfall, particularly in northern areas. Strong winds may also develop during this period. As March draws to a close, high pressure is expected to dominate, leading to dry weather with potential overnight fog and frost.