On Sunday, 26 May 2019 20:38:33 UTC+1, Nick Gardner wrote:
Today and yesterday have seen quite high UV levels after what has been a
spring season of rather normal UV intensity.

The lack of tropical maritime air masses has probably been responsible.

The UV here today reached 8.6 despite quite cloudy and hazy conditions
with the sun always being partly obscured by haze or cloud. Yesterday's
hazy conditions saw the UV reach 8.0.

I suspect that now the CF has moved through this evening and we're in a
different air mass, the UV maximum tomorrow will be down to around 6.0
to 7.0.

Given the forecast for later this week, we may see an extremely high UV
level of +9.0 on Wednesday. Slip, slop, slap...oooerrrrr.

--
Nick Gardner
Otter Valley, Devon
20 m amsl
http://www.ottervalleyweather.me.uk

UV levels are not related to temperature so they would not be lower because of a colder air mass and they would not be higher because of a warmer air mass. They relate to the position of the sun in the sky. At this time of year, it is at its highest point at 1 pm and this is when UV levels can be high.

Nicholas
Meir Heath, Stoke-On-Trent 250 metres above sea level.