The Met Office said it would be a “dry and fine” day for many with warm spells of sunshine.
The highs of 17C mean the UK will be even hotter than the Greek capital of Athens despite forecasters warning that there could be some early morning fog and frost across the southwest.
Met Office meteorologist Aidan McGivern said: “Touch of frost first thing. But soon it will warm up.
“Some sunshine around where we have the lowest temperatures.”
But large parts of Scotland will be cloudy, threatening to keep temperatures in the low teens.
“Not everywhere will be sunny though, a lot of strengthening cloud cover in the north of Scotland with gales for the north of Scotland”, he added.
Temperatures in London are expected to hit 17C, making it warmer than the Athens where highs of 14C have been predicted.
“Otherwise a fine day for most with warm spells of sunshine and light winds,” the forecaster said.
But the balmy temperatures won’t last long as Arctic weather is back this weekend with storms and snow expected for some of Britain.
Weather Outlook maps show snow coming to the UK on Saturday morning.
BBC meteorologist Simon King said: “Going into the weekend that rain in the north-west is all linked in with this cold front.
“Gradually during Saturday it’s going to push its way south and eastwards.
“Temperatures will drop and it will be much cooler into next week – also the risk of some wintry showers.”
There is a risk of gales in the north this weekend too, the Met Office said.