The Met Office confirmed snow fell in Exmoor in south-west England on Tuesday morning and then spread throughout the day.
The Brecon Beacons and Pennines have also been affected, while other high ground areas have seen wintry showers.
Though it was mainly hilly areas being impacted, Met Office meteorologist Alex Burkill said lower areas could see the same in coming hours.
"It's mainly over the higher grounds where we've seen anything long lasting," he told the Standard.
"But I couldn't rule out it going to the lower grounds, even parts of the south east.
"Elsewhere there will be some pretty heavy showers.
"Through the next 24 hours, most likely to see any wintry showers."
By Wednesday evening the snow is expected to have passed for now.
Mr Burkhill said people will not wake up to blanket snow as it is not expected to settle anywhere strongly.
“It’s quite wet, so it’s quite slushy,” he said.
The coldest recorded temperature on Monday night was -0.5C in Inverness-shire, Scotland, but the mercury will drop as low as -1 or -2C on Tuesday.
Temperatures will drop particularly low in the south, while overnight showers will continue meaning the risk of a few icy patches by Wednesday morning.
From Wednesday, there will be strong cold winds in the north and west, though it will get dryer.
Then as the end of the week approaches, showers will return in the east and south west, some of which are still expected to be wintery.
