On Monday, May 25, 2020 at 2:25:39 PM UTC+1, Nicholas Randall wrote:
I noticed on the Met Eireann Twitter account and website there was a mistake which stated if the UV index was 10 it was extreme. I contacted them using the form on their website and had emails asking me for evidence it was wrong. I took a screenshot from their website but they wanted more evidence so I took a screenshot from the World Health Organization website which stated the UV index is extreme if it is 11+. Met Eireann corrected it on their Twitter account and website before I sent the email and I am pleased it has been corrected but surprised by the mistake.
I have stated before the UV index does not exceed 8 in the UK as this is what I read on the Met Office website and DEFRA. I look at the Met Office website and the temperature forecasts are too low and this makes me think the UV forecasts are also too low. Two people on here have told me UV levels in the UK have been higher than 8 so I was wrong.

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

The UV index regularly reaches 8 in Cornwall, and has reached 10 at Camborne (which is of course a MetO station) on a few occasions. 11 has been recorded out on Scilly. I believe Nick up in Devon (part of England I believe) has also recorded 10.

The very high readings are normally associated with a warm sector ridge & a very gentle SW airstream. Cold sector deep blue skies invariably give significantly lowing readings.

There have been discussions on why this is the case, whether it is due to low levels of ozone under warm sector conditions, or low level high humidity..

Certainly, the times I've been badly burnt have always been is sea misty conditions. Other people on here have made the same comment.

Graham
Penzance