Sun Strength

[Thundery wintry showers]

I rarely need sun protection until well into April, but that's because I'm rarely out there "sunning myself" with bare skin for long periods. When the latter does happen, though, I can burn in mid-late March, and I remember a particularly emphatic example at the end of March 2004 when I spent long periods outdoors on a field trip and came back quite red.

For me the "sunburn period" can be categorised as falling broadly between the equinoxes, 21st March-ish to 21st September-ish.

[Scorcher]

It looks like we will see a UV index of 3 in my area next week, things are looking up!

[Snowyowl9]

It usually takes until early May for the sun strong enough to start burning or a suntan,or April 2007 of course an exceptional sunny hot month april 2003 aswell,or a large snowcover of 9 inches will do it like in 2000 when the sun comes out,it was dazzlingly bright. :lol:

http://www.wetterzentrale.de/archive/ra/20...00120000403.gif

Edited March 14, 2009 by Snowyowl9

[Scorcher]

You can easily tan with a UV index of 3 if you're out in it long enough. I'm not sure why people think you can't get a tan until May. Just because it's not warm enough to sit outside doesn't mean the sun isn't strong enough to tan you. Most people in this country would notice the effects of the sun on their skin from the beginning of April if the sky was clear and they were out in it long enough.

Edited March 14, 2009 by Scorcher

[Derp Patrol]

All 2's are forecast for the coming 5 days here, the first 3's are starting to show up in Plymouth :lol:

Can someone tell me in general when we can expect 4s,5s,6s in the UV Index to start coming? Also does anyone know the highest it has been in the UK? is it possible to be higher than 7 here? Thanks.

Regarding tanning, usually I can tan from Mid April onwards.

[Thundersquall]

I'm not sure why people think you can't get a tan until May.

Precisely! What people forget it that the Sun is as strong at this time of year as it would be in late-September.

In April the Sun's strength will be as powerful as it would be during August. That should get us thinking about putting the sunscreen on!

Edited March 14, 2009 by Thundersquall

[SP1986]

The sun at first today was quite warm but when the breeze blew it was so cold you couldn't feel the strength of the sun. A little too early to say the sun is strong. Whilst winter is still with us in terms of cold breezes, the sun will not be at it's full power, even for this time of year. This may change in the next few days but for my location it will stay pretty cool perhaps, so I'm not sure I'll feel the full strength of March sunshine.

[Nick L]

All 2's are forecast for the coming 5 days here, the first 3's are starting to show up in Plymouth :lol:

Can someone tell me in general when we can expect 4s,5s,6s in the UV Index to start coming? Also does anyone know the highest it has been in the UK? is it possible to be higher than 7 here? Thanks.

Regarding tanning, usually I can tan from Mid April onwards.

Welcome to NW. Just had a look round the Met Office site, they say we can reach 7 and in exceptional cases we can get 8s in the south around the Summer Solstice, but due to our northern latitude that is the limit.

[J07]

All 2's are forecast for the coming 5 days here, the first 3's are starting to show up in Plymouth

Can someone tell me in general when we can expect 4s,5s,6s in the UV Index to start coming? Also does anyone know the highest it has been in the UK? is it possible to be higher than 7 here? Thanks.

Regarding tanning, usually I can tan from Mid April onwards.

I think 8 is the all time record for the UK. You won't see 6 until June.

[lizziek]

Well I'm very fair and so is my husband - we stood outside for a good 5 hours yesterday and both of us now have pink faces!

[Bottesford]

All 2's are forecast for the coming 5 days here, the first 3's are starting to show up in Plymouth :o

Can someone tell me in general when we can expect 4s,5s,6s in the UV Index to start coming? Also does anyone know the highest it has been in the UK? is it possible to be higher than 7 here? Thanks.

Regarding tanning, usually I can tan from Mid April onwards.

A warm welcoem to netweather!

From my memory - 7's usually appear just around the summer solstice - up to maybe 2 weeks either side. The Midlands is about as far north as they go.

6's are late May to late July, 5's May to August, 4's April to Sept and 3's between the equinoxes - this applies to the Midlands southwards and is not far off guesswork!

[J07]

A warm welcoem to netweather!

From my memory - 7's usually appear just around the summer solstice - up to maybe 2 weeks either side. The Midlands is about as far north as they go.

6's are late May to late July, 5's May to August, 4's April to Sept and 3's between the equinoxes - this applies to the Midlands southwards and is not far off guesswork!

That all sounds pretty much accurate. Even in that "window of 7s" they are not all that commonly forecast. I'd like to find a link that gives actually measured UV indices across the UK in summer. Would be interesting to see how they vary depending on what is forecast.

Here, the clear sky indices tend to be roughly 7 on the equinoxes, and roughly 14 on the solstice.

It seems we frequently: http://www.netweather.tv/forum/index.php?showtopic=51089 record UVI that is higher than forecast, by a fair amount. So I'd be interested in whether this happens in the UK also. But the MetOffice don't seem to show actual measured UVI, only forecast.....

[conor123]

This is a bit of a stupid question probably but say it was around Late June, with clear skies, would you been more likely to suntan/burn at 21c or 31c.

Or does it not make a difference?

I always thought it doesnt make a difference but people always assume your more likely to get sunburn in higher temperatures so confuses me somewhat.

[Backtrack]

This is a bit of a stupid question probably but say it was around Late June, with clear skies, would you been more likely to suntan/burn at 21c or 31c.

Or does it not make a difference?

I always thought it doesnt make a difference but people always assume your more likely to get sunburn in higher temperatures so confuses me somewhat.

Well, at 21c that is very much bearable, you could sit out all day, but at 31c you couldn't be out for more than a few hours without going inside because of the intensity of the heat. But it all depends on the time of day and strength of the sun, I'd say 31c though.

Edited March 15, 2009 by Hancock

[Snowyowl9]

You can can sunburnt more with a total snowcover at this time of year,I`ve never got sunburnt in march or september,mid april onwards when it starts to take effect,I don`t stay in the sun for long anyway from early May onwards it`s not the heathiest thing at all.

[Bottesford]

Would make no difference - temperature has no effect on UV light levels. Cloud cover, solar position, ozone layer state and air transparency would be the factors to consider.

But temperature does have an indirect effect though. More people get burnt in August than in April despite the sun being in a roughly similar place at any given time of day. This is because August is warmer so more people are sat outside with less clothes on. April sun, strong as it can be, is often accompanied by cool air where most folks are still in a jacket and not sitting around outside.

[Andy Bown]

Ones' face has caught the sun this weekend. Two sparkling days !

[Nick L]

This is a bit of a stupid question probably but say it was around Late June, with clear skies, would you been more likely to suntan/burn at 21c or 31c.

Or does it not make a difference?

I always thought it doesnt make a difference but people always assume your more likely to get sunburn in higher temperatures so confuses me somewhat.

That's the problem. When it's around 20c in June and the sun is blazing, people don't find it so hot and presume they don't need sun screen. But the truth is it could be -10c (in June yes it won't happen) and you will still burn without protection.

[Grimsby Snow Lover]

Some very interesting posts on here tonight. Never knew the sun has as much strength now as in late September. I suppose the difference is in the daytime temperature as it is much warmer in September than March generally. I noticed the increasing strength of sun this morning when I was power washing the drive it felt really warm away from the breeze. No sun tan though.

Edited March 15, 2009 by Grimsby Snow Lover

[Derp Patrol]

Thank you for the answer :lol: I tend to find that I tan in July/August more than any other month, I think the heat just makes people wear less protection so they are more prone to sunburn. I was out today and I think I cought the sun a little bit, when there was no breeze, the sun did feel strong.

[reef]

Would make no difference - temperature has no effect on UV light levels. Cloud cover, solar position, ozone layer state and air transparency would be the factors to consider.

But temperature does have an indirect effect though. More people get burnt in August than in April despite the sun being in a roughly similar place at any given time of day. This is because August is warmer so more people are sat outside with less clothes on. April sun, strong as it can be, is often accompanied by cool air where most folks are still in a jacket and not sitting around outside.

This is true, however one thing Ive always wondered is how ozone levels affect things. Doesnt a cold stratosphere generally mean lower ozone levels? Essentially that would mean that with the stratosphere much colder in April than in August, you would actually be more likely to burn in the former than the latter. Theres also the fact that by August many people's skin has seen the sun at least a few times, so tends to be a little more resistent than earlier in the year.

Personally I have very fair skin, so can burn anytime from March to October. I managed to get burnt in mid-October 2005 (rather embarassingly). I also got heatstroke and sunburn in August 2003 from working outside for 9 hours (despite copious amounts of sun lotion). I suspect the temperature (32.0C!) was more to do with how bad I felt the next day though.

[SP1986]

You should always watch out for high level cloud too - many people think that high level cloud reduces the strength of the sun and indeed it may reduce the warmth of the sun but it may magnify the the intensity of the sun. Today is a great example, there sun shining but milky high cloud - it'll be interesting to see how many people have been burnt on here today come this evening.

[summer blizzard]

Yesterdsay was glorious here, however what shocked me the most was that even at 09:00, when standing still i could feel the power of the sun, had i been outside a few hours, i'm sure i could have tanned.

[❄️❄️❄️❄️❄️❄️❄️❄️❄️]

When is 20C generally possible under clear skies and high pressure?

[reef]

When is 20C generally possible under clear skies and high pressure?

From high pressure overhead, generally mid-April onwards (though there probably are a few exceptions). The main problem early in the spring is that the clear high pressure required tends to give cold nights, so the temperature has to recover more during the day. Early season warm spells generally come from Bartlett highs and southerly setups. They have the advantage of mild upper air and less cooling at night.

2nd March 1977 was such an example, when Exeter Airport reached 20.2C - the earliest date in the UK to top 20C:

http://www.torro.org.uk/TORRO/britwxextrem...syear.php#March

That was from a Bartlett setup, with +12C touching the south-west. Looking at the charts it would probably have been rather sunny too, though poorer the further north and west you were.

http://www.wetterzentrale.de/archive/ra/19...00119770302.gif

http://www.wetterzentrale.de/archive/ra/19...00219770302.gif