J07

If it's for your own records then of course no one can stop you accepting the 33.9C. But these things happen all over the world, there's always claims that it's much warmer here than x miles down the road, and very often these claims don't stand up to scrutiny! For quite a while, there was a temperature somewhere in Australia of about 54C, and when it was investigated turned out it was a farmer with a thermometer dangling from his porch, completely sun and building contaminated. And these unofficial claims have a way of getting out, as we unfortunately saw in a bloody newspaper headline this year!

No one is questioning whether the equipment is correct, the issue is that it's not got good exposure. Given the behaviour of official stations around the country, it's likely this one is influenced by nearby buildings, hence it's not got standard exposure and would never be counted as official. These comments: "It can't be wrong either because the guy across the road from me said he has a weather station aswell and he said it was reading 93f this afternoon." ; "when I was outside in the sun this afternoon it felt like no heat I had ever experienced before" , whilst not "wrong" are meaningless for corraborating the relevance of the station. What do you think would happen if someone had a station in their backgarden of a terrace house in London today, or in any other hot spell? Records would be smashed for sure. Surely it is correct that the station in question DID record 33.9C. But that is not the point. If we started allowing for these stations in records across the world, then our decades/centuries of records would be rendered worthless, and our whole understanding of temperatures would change. 30C would no longer sound hot, because there would be a wealth of unofficial stations recording 35C.

The answer, it appears, is very little. These are recorded UV indices from Homestead in southern Florida and Lauder/Alexandra in southern New Zealand. The period of 15th Dec - 15th Jan in NZ and 15th Jun - 15th Jul in Florida. The difference in latitude is 25N vs 45S. Total number of 11+ UVI Days (classed as "Extreme") is 24 in Alexandra, NZ and 18 in Homestead, FL. Also, compare with Davis, California at 38N- because summer is their dry season there so plenty of clear skies. The number of extreme UV days there was only 1. Holtville, at 32N shows a similar pattern. The Michigan graph shows a station at similar (modest) altitude and latitude to Alexandra, yet the difference is quite acute- with no double digit UVIs being recorded there. These readings at a glance support the idea that UV down under is approximately 40% greater than at the same latitude in the northern hemisphere. The Utah site is at 1400m ASL, and at 41N, yet again is not really comparable. Essentially to get higher UV indices you have to head down to both 32N and get up ~1400m above the surface, as shown by Las Cruces. The other option would be to head into the tropics and remain at sea level. For "entertainment" sake, have a look at Mauna Loa in Hawaii. It's in the tropics and it's 3400m ASL. The UV there is truly terrifying!

Poor Gorillas. They're probably thinking "where I come from it's hotter than this in winter, but hey....free food".

I'd expect that sort of sensationalist stuff from the Mail or Express, not so much from the Times. They just ignored the humidity completely. BKK seemed to reach 29/23 yesterday, whereas London saw 30/12. Now, which of those feels hotter! It's pretty obvious isn't it!

I know, I was in the UK for August 2003, didn't know what to do with myself!

Yeah I know, I'm not making allowances for the horrors of British homes in warm weather! The London humidity at the peak of the day was very low (33%) and Bristol 61%. It's different now though because RH tends to hit its lowest during peak temperatures. In many places now, temperatures seem to be 21/18 or so, which is RH of 83%.

It seems like it's hot and dry in the southeast, warm and humid further west. London's air was even drier today than yesterday, with 30/12, but I saw Bristol had a muggy 26/18 which is probably more unpleasant. Still not exactly "tropical" or similar to the US deep south or southern China though.

Looks like 850hPa temperatures could creep up to 15C over the next few days. After that, if the EC is to be believed then a fairly bland period of weather coming up post-heat.

Here's the Heathrow Metar from hottest time of the day. Really rather dry air there, 33% RH, so no sign of this much maligned humidity. During the warm part of the day, RH never actually got above 50% and dewpoints never above 15C. EGLL 291550Z 12009KT 070V150 CAVOK 31/13 Q1017 TEMPO TSRA = Bristol Airport got to 25/18 apparently. That is quite muggy. It would be considered typical conditions for the tropics in the depths of winter. Noumea reached 24/18 yesterday, it's mid-winter there and those are quite average conditions there. So when people talk of "tropical" feeling weather in the UK, I think except in exceptional spells, it's only really fair to compare it to the tropical winter/dry season when the air is drier and less oppressive.

A little surprised by how low the dewpoints are at the moment. 28/13 is fairly dry.

Sunday in summary across NZ: Highest Maximum Temperature: 19C in Kaitaia and Whangarei Lowest Maximum Temperature: 0C in Alexandra Highest Dewpoint: 17C across Northland At 9AM it was -4C in Christchurch and 17C in Kaikohe. These are quite big spreads for mid-winter in a maritime country. It's due to a tropical outbreak over the north. A slow moving low has been able to pull air down from inside the tropics, and this has made quite a difference to regions that have been recording frosts and clear, cool days for a few weeks now.

That was excellent. I wonder what was on his mind - a Glastonbury toilet experience? A dodgy curry from the previous night? Or....just an innocent slip of the tongue.

Rubbish in Oz: Good in NZ:

Well, really, there are worse places for storms in the UK than the SE. Crikey, what carry on! As for this 33C+ stuff. How often does that happen? I'd bet if you took averages for the last 30 years, it probably comes out at about 1 day a year that exceeds 33C. In the meantime, you have 364 days when you can be slightly happier.

Same old, same old. Partly cloudy, 9C. High of 11C. Few showers at times. Strong southerly winds. Meanwhile some parts of the country have been enjoying stunning weather for days. Found this photo on another forum...an obscure corner of the North Island on the winter solstice.

I think they got to 2C at the airport, but no doubt lower away from the sea. This high is very slow moving. Auckland's forecast for the next 5 days is "Fine with light winds (or southerly breezes), with highs of 13C and cold clear nights with frosts in sheltered parts. That's perfect winter weather if you ask me! NZ is a little larger than the UK, but it is "longer" and so that probably contributes to the variation. Other factors are the more extreme terrain, the speed of depressions to our south, and that both the polar jet and subtropical jet have direct affects on our weather.

Scotland - don't think they will get higher than whatever it was they got in May (27C?) Wales - 30C NI - 28C England - 33C

I think in the 1960s, Auckland Airport managed to get down to -3C. How, I don't know. Tomorrow night looks like the cold one for them. They get cold nights when there is a southerly flow (cold, dry air off the central plateau) and then the southerly dies overnight leading to plunging temperatures. In that case not even their strong oceanic influence can save them. Tonight won't be all that cold, tomorrow is the one to watch Wellington historically is milder than Auckland. Lowest temperature here ever is -2C, and that was back in the 1920s. Coldest day ever still managed to reach 5C. Currently, at 11PM the coldest place is Waiouru on -6C and the warmest Cape Reinga on 10C.

Try rubbing vaseline around the edge of your eyes, and smearing it in your nostrils.

What happened? I can't remember. Was it the November floodings?

Another cold outbreak heading our way. We've been in a warm situation for a few days now, with nationwide highs hitting 20C at times in the north. Dewpoints have been as high as 16C up there, making it more autumnal than wintry. Warning for heavy snow down south: SEVERE WEATHER WARNING. ISSUED BY MetService AT 8:04 pm 14-Jun-2009 MEDIA HEAVY SNOW EXPECTED FOR SOUTHLAND, SOUTH OTAGO AND DUNEDIN An episode of very cold showery conditions is spreading onto southern New Zealand and should persist well into Tuesday. In Southland, south Otago and Dunedin, snow is expected to develop to low levels on Monday, although initially, no large accumulations are expected.However, on Monday evening, snow is expected to lower to sea level,and a burst of heavy snow is likely overnight Monday to Tuesday.During Tuesday, snow levels should rise slowly, as the activity eases. These conditions are expected to cause disruption to many roads.Strong or even gale force southwest winds about exposed coastal areas and the hills, are likely to lead to blizzard conditions with heavy drifting snow and very low wind chill temperatures. FOR THE LATEST WEATHER AND FORECAST CHARTS PLEASE GO TO http://metservice.com MORE DETAILED INFORMATION FOR EMERGENCY MANAGERS AND TECHNICAL USERS FOLLOWS: HEAVY SNOW WARNING AREA/S AFFECTED: SOUTHLAND SOUTH OTAGO AND DUNEDIN FORECAST: In the 42 hours from 3am Monday through to 9pm Tuesday, up to 25cm of snow could accumulate above 200 metres. Lighter falls are expected down to sea level,where 2 to 5cm could accumulate during this period. Heaviest falls are expected between 6pm Monday and 3am Tuesday, when up to 15cm of snow could fall above 200 metres. Blizzard conditions and heavy drifting snow can be expected in places.

AFAIK, a few things contribute (at least): Ozone depth, latitude, time of the year (ie distance from the sun), pollution and cloud. I really know little about how ozone depth varies, but obviously the layer is very shallow near the Ozone hole and when parts of it break off. Elsewhere, I think typically there is less ozone in the tropical atmosphere than in temperate regions. I don't know what governs the day-to-day movement of different depths of ozone. Where do you get your UV forecasts? It sounds like it's pulled straight out of a computer model, which is probably trying to juggle a few different variables at once. See the two attached files for an example of the type of thing we get down here. It's also trying to take into account the cloud, but I don't know how sophisticated is the cloud model. Clearly it recognises different depths - with the UVI being 8 underneath one area of cloud but 5 under another area. Yours are clear sky forecasts, I wonder if it's just translating forecast ozone depth directly into a surface UVI? But I found that UV forecasts can be just as wrong as temperature forecasts, at least down here anyway. I suppose you would get your highest UV within 2 weeks of the Solstice. Worth noting that the sun angle changes *very little* around the solstice, so being bang on June 21st is probably not much different to being in the first week of July when it comes to UV. Highest UVI ever recorded in the UK was 8, somewhere in the South...don't have it to any greater accuracy than that. UVI would be limited by the relatively polluted atmosphere over the British Isles, the high latitude and low sun angle, and the fact that the Earth is furthest from the Sun around July 4th - hence the seasons are "backwards". I don't have any sources at hand, but I think the highest sea level UVI was 17 in Carnarvon, Western Australia but mountainous tropical regions in the Southern Hemisphere (eg Andes, PNG) get UVI up to 25. The "high cloud magnifies UV" is a mystery to me, I've often heard it but really don't know.

Yeah. That happened to me once.

When did the UK last hit 20C? I've been looking at "the last 24 hours" for the last two days and none of them saw 20C anywhere in the country.