UK could see temperatures as high as 20C

Temperatures in parts of the UK could climb as high as 20C, as forecasters predict Wednesday could be Britain's warmest day of the year so far.

The Met Office said there will be spells across most of England and Wales on Wednesday, and Britons can expect to feel warm in the sunshine. The warmer weather coincides with the spring equinox on Friday - when the day and the night will be equal in length as the sun crosses the celestial equator - signalling the arrival of longer days and higher temperatures.

Dan Harris, chief forecaster at the Met Office, said: "Wednesday looks likely to be the warmest day of the week for many, with high pressure dominant. "The warmest spots are likely to be in parts of west Wales and western England, where under sunny skies, 18C to 19C, possibly even 20C is on the cards.

"This is due to the additional boost expected from the passage of east to south-easterly winds over areas of higher ground, known as the Foehn effect." Wednesday could bring the highest temperatures of the year so far, after Kew Gardens in London hit 18.6C and Kent and Suffolk also topped 18C on 25 February. Tuesday will be more unsettled across much of the UK, with rain moving east throughout the day, though the far south will likely stay largely dry, the Met Office said.

Temperatures on Tuesday will be about 13C to 15C across England and Wales, 11C to 13C in Scotland and 13C in Northern Ireland. But skies will clear across England and Wales on Wednesday, bringing sunning spells and warmer weather during the day but colder temperatures at night.

Read more from Sky News:Will first UK nation legalise assisted dying?'Stop blaming Brexit for economic woes' "There'll be a big diurnal range this week, which is the difference between the maximum daytime temperature and minimum overnight temperature," Mr Harris added. "Thanks to the clear skies during the day, we'll see some chilly nights after the warmer days with a few places experiencing air frost." Scotland and Ireland are forecasted to see temperatures between 12C to 13C on Wednesday, with Belfast expected to see temperatures of 14C.

Thursday is expected to be dry and settled with more sunshine, though temperatures will cool towards the seasonable average on Friday. Last week saw the UK return to wintry conditions, when a blast of Arctic air swept across the country bringing freezing temperatures, strong winds and changes of frost and snow..