I wonder if the deep shades of blue have anything to do with tbe reduced amount of planes in the sky.

Yes but on the same page it admits the forecast can still be lower than the actual levels, as O3 is unpredictable at certain times of year.

It quotes March/ April but there seems to be evidence of unusually low O3 overhead at different times of the year too.

I think you have missed the point. The point was just because they are forecasting on the automated forecasts an 8 it doesn't mean that is what is expected as they automatically rounded it up.

The 8's on the forecast maps or in reality the 7's that have been at times widespread over past weeks will be due to lower then normal ozone above.

Friday forecast:

8s for the most of S England & S Wales ; 7s up into the Highlands, even N of Aberdeen.

6 for the N of Shetland. As good as it gets (apart from the rare 9s in S Devon Retron sometimes spots!)

https://www.metoffice.gov.uk/public/weather/forecast/map/gcp1by0nd#?map=MaxUVIndex&fcTime=1590710400&zoom=9&lon=-1.23&lat=60.59

Chilton 7.5

Reading 7.8

Camborne 7.9

Reading 8.0

Camborne 8.1

Chilton below 8

8s forecast today as far as the far N of Wales and N Lincolnshire; and tomorrow- as far as Dentdale in N Yorkshire!

https://www.metoffice.gov.uk/public/weather/forecast/map/gcp1by0nd#?map=MaxUVIndex&fcTime=1590796800&zoom=9&lon=-1.86&lat=54.20

Don't think I've seen it forecast as far N as that. Linked to the clear air of the Dales?

Camborne & Reading both 8.0

Chilton 7.7

7s forecast as far N as Wick and even Thurso.

Surely reduced pollution under lockdown has impacted on this? It's quite late now for the spring 03 thinning, but regardless, I haven't seen 7 forecast for the far N coast of Scotland before.

https://www.metoffice.gov.uk/public/weather/forecast/map/gcp1by0nd#?map=MaxUVIndex&fcTime=1590883200&zoom=9&lon=-3.47&lat=58.39

Last two days Reading: 7.6, 7.8

Reading: 17 days so far this year with a UV of 7 or more. 

After a darker spell, Reading has managed 7.2 today and Chilton 7.5

That's 20 days of 7+ with an 8 on 5th.

Seems I was premature about Chilton yesterday- 7.8; unless this is yet another data service subject to adjustments. Best if data is not published provisionally- not much point in it.

8 forecast right up to N Yorks and beyond, to Barnard castle in Teesdale (County Durham) on Wednesday!

https://www.metoffice.gov.uk/public/weather/forecast/map/gcp1by0nd#?map=MaxUVIndex&fcTime=1592956800&zoom=9&lon=-2.19&lat=54.70

Thanks Darren- it's always you that spots them first!

Add - 3 days' worth forecast for Jersey; still impressed.

They've made it to England now - screenshot attached, as it'll probably come and go as the forecasts update through the day!

(Click for full size)

Yep; interesting this time that most of Cornwall is included by Wednesday:

https://www.metoffice.gov.uk/public/weather/forecast/map/gbvmf1rg9#?map=MaxUVIndex&fcTime=1592956800&zoom=9&lon=-4.60&lat=50.27

And it extends into Dorset (as far N as Gillingham) and Somerset (Wincanton)as well. Amazing.

8s as far as Durham including almost all of England and the whole of Wales; and 6 in Sella Ness in N Shetland.

The 9s are gone by Thursday. I wonder if the Channel Isles will ever suggest a 10.

Edit- unlikely as even the resorts of SW France like Biarritz are only up for a 9!

Reading 8.3

Chilton 8.7

FWIW, the latest model run has 8s into Scotland... not sure if I've ever seen them that far north before.

Could be quite a shock in store for our northern contingent if that comes to pass!

Today's highlights: 8.6 in Leeds and 7.0 in Lerwick. Both could be records.

Incredible.

The whole of Cornwall, most of Devon and most of Dorset forecast 9 today!

Another day, another jump north - with an 8 popping up in Aberdeenshire!

Can anyone beat that in terms of northerly 8s?