UK temperature reaches 21C in warmest day of year so far
On Wednesday, a temperature of 20.9C was recorded in Gogerddan near Aberystwyth, marking the warmest day of the year so far in the United Kingdom.
England also experienced its highest temperature of the year to date, with 20.2C recorded at Northolt, London.
Temperatures across England and Wales have widely reached the high teens, representing the warmest spell of spring weather so far this year.
Extended periods of sunshine are expected to increase UV levels, while rainfall is forecast to remain minimal for most areas over the coming week.
Criccieth, Gwynedd and the surrounding area have recorded the warmest weather of the year so far, with temperatures reaching up to 20C.
Foehn effect boosts temperatures
The warmest locations on Wednesday included west and north-west Wales, London, and the north coast of Cornwall.
Temperatures in west and north-west Wales have been elevated due to the Foehn effect, a meteorological phenomenon.
This effect occurs when air passes over a mountain range—in this case, the Eryri and Bannau Brycheiniog mountain ranges, formerly known as Snowdonia and the Brecon Beacons.
As moist air ascends the windward side of the mountains, it cools and condenses, releasing moisture.
The now drier air descends the leeward side, warming as it compresses.
Because the air is drier and its thermal properties have changed, the temperature becomes higher than it was initially.
How strong will the sunshine be?
At this time of year, near the spring equinox, day length increases and the Sun rises higher in the sky, causing sunlight to feel stronger.
With mostly clear skies forecast, UV levels are expected to rise to medium across England, Wales, and eastern Scotland on Wednesday. Cloudier conditions will keep UV levels low in other regions.
It is important to note that during spring months, although temperatures are not as high as in summer, ultraviolet (UV) levels in late March can be as strong as those in September.
While small amounts of UV radiation are necessary for vitamin D production, the World Health Organization warns:
"Overexposure may result in acute and chronic health effects on the skin, eye and immune system".
The NHS advises balancing sun protection with adequate vitamin D synthesis by spending time in the shade between 11am and 3pm and wearing suitable clothing and sunglasses.
Monitoring UV forecasts via the BBC Weather app or website is recommended.
Sun protection is advised by the World Health Organization once UV levels reach the medium category.
- What and when is the spring equinox?
- Spring is the 'fastest-warming' season in the UK
