Between the showers the sun did have a bit of a 'bite' to it today? I suppose that's P.M. air for you? ( or my winter white skin taking in its first rays of the year?)

Yesterday and today, Reading: 2.8 and 1.8. Great 3+ in the Forest, Roger!

12th and 18th June 2000 must have been faulty readings, surely: well over 9 in both cases at Reading. A crestfallen moment here. 

4,2.here yesterday in strong sun, 3.8 today. 

Reading's readings since 23rd:

3.1 on 23rd; 3.2, 3.6, then an amazing 4.0 on 26th. 

Then 2.9, 3.2, 3.2.

Notice MetO have published a sensible caveat with forecast UV maxes: the normal average expected, etc etc. with additional acknowledgement of ozone variations etc. 

No data yet for Reading today. Camborne 4.0 and Swansea 3.9 though.

3.8 today

I'm not sure why you find 4 in very late March amazing as it's rather normal as a top UV if conditions allow in the South... During low ozone UVs can be high.. 6 and 7s in April kind of high.   

At that point (26th) the sun would have reaching the same angle as it will be around 17th of September. 

You overlook the fact that the data I've reported is for Reading, not the S Coast, where I am sure you get an earlier edge. As for normal, potentially yes, but in reality no- in fact, it has occurred in only a quarter of years since 2000. By definition, that makes it anomalous rather than normal. If you scroll back through Reading's data, you will see there have only been 5 years since 2000 (20 year period) when 4 has been achieved: 2002, 2003, 2011, the amazing March of 2012, and this year. But the thing is, 2019 is the earliest date during that period when it has been achieved. It has been significantly exceeded in March in 2002- that's amazing for it's extremity. In 2012 there were several 4+ days- that's amazing for its frequency; in 2019 it was achieved on 26th- that's amazing for its earliness. Different reasons for me to be amazed. 

As for 7 in April, that was achieved only twice in the same period, in 2000 and 2002, with near misses on two days in 2013. All this again shows the potential, but to call it normal is much further from the mark than calling it amazing.

There's currently an index of 5 being forecasted for Thursday down here. A reminder I think that summer is only around the corner now. 

Excellent; bring.

UV4 forecast as far north as the Isle of Mull today. Hard to believe that there are no 5s forecast in the far south/ southwest.

https://www.metoffice.gov.uk/public/weather/forecast/map/gcp1by0nd#?map=MaxUVIndex&fcTime=1554854400&zoom=9&lon=-5.36&lat=56.18

Reading has been offline sts since the 7th; but Chilton has just managed its second 4.4

Camborne reached 5.0 yesterday. Still no data from Reading.

Perhaps the first low ozone event of the spring down here on Saturday.

A UV of 6 is on the menu which is high for the 3rd week of April where typically 4-5 are normal. I wouldn't expect a 6 until at least early May.

Impressive, although it seems the MetO have downgraded to a 5 today, but well inland also.

https://www.metoffice.gov.uk/weather/forecast/gcp1pu361#?date=2019-04-21

Still High by their grading (5 and 6 are high; click 'more detail' beneath to see the actual forecast 1300BST values).

Do we know if 'global Dimming' has shown impact on the record of U.V. Values over the decades?

If we are again moving in the right direction with regard sulphate/particulate pollution could we expect higher U.V.'s over the year due to more getting down to the surface?

I'm only asking as the only 'ozone hole' I'm seeing near us is up between Iceland and Svalbard and we are at pretty normal in our values over the UK?

I think you're right Gray about the O3 hole being more or less over the Norwegian Sea- a normal location in spring/early summer; but it sometimes migrates south (think it did last year at some point and 9s were forecast over Devon). Not sure about particulate pollution- makes sense though.

No 5 is moderate by met office grading.

3-5 moderate 

6-7 high

8-10 very high

https://www.metoffice.gov.uk/weather/guides/what-does-this-forecast-mean

You are absolutely right Pictures; and I note (in the link) how the UV has been downgraded to a moderate. I think they must have downgraded the numbers first, then the category. On a plus note, 5s are forecast as far N as Bridlington on Saturday. Wouldn't surprise me if somewhere IYNOTW got a 6- or maybe S Devon, IOW or the Channels.

I'm confused as to what you mean as a 5 has been classed as moderate for a fair few years now Bert. Don't forget these things are all automated and change multiple times a day :)

What I mean is, I think I must have looked at roughly the time when the 6 changed to a 5, saw the H for High still, then a short time later looked at the 'more detail' section and put the two together; thus, I equated the 'High' to the 5, when in fact, as you say, it is moderate.