00:00The real question is, are we going to see the fourth heat wave of the summer?
00:05Now let's not forget, for it technically to be a heat wave,
00:09we do need to see temperatures of between 25 to 28 degrees Celsius,
00:13depending on your location in the UK,
00:15so a little bit higher across central areas and parts of the southeast.
00:19And we need to see those temperatures or higher for three consecutive days.
00:23Now temperatures look like they're only up from Sunday onwards,
00:26but there's still a little bit of a question mark as to how long the heat could last.
00:31Nevertheless, whether it's a heat wave or not, temperatures are going to be on the up.
00:36So here we have temperatures compared to the climatological average here in the UK.
00:41And you can see already from these charts,
00:44these are daytime temperatures along the bottom from Sunday to Wednesday,
00:48and these are overnight temperatures from Sunday night through into Tuesday night.
00:51So it's not just the days that are going to be warming up, it's the nights as well.
00:55And you can see quite clearly already, day-to-day temperatures are on the up,
01:00shown by these slightly darker red colours.
01:03So initially on Sunday, the bulk of the heat is going to be across central England,
01:07parts of the southeast, east Anglia, London in particular.
01:10We're going to start to see temperatures pushing through into the high 20s.
01:14And then from Monday onwards, there's a good chance that we'll start to see temperatures push into the low 30s as well.
01:19Once again, initially across central parts of England on Monday, parts of the southeast,
01:23but this time pushing a little further north, parts of Yorkshire, Lincolnshire too,
01:27could start to see those temperatures push up into the high 20s.
01:31And then we really do see that intense heat push through on Tuesday.
01:34That's likely going to be the peak of the heat, Tuesday daytime.
01:37Well, we'll start to see those temperatures around 30 degrees, if not a few degrees more,
01:42probably around a 10% chance that we could push up into 34, possibly 35 degrees Celsius.
01:47And similar on Wednesday.
01:50After that, there's a little bit of model spread, a little bit of uncertainty as to if we're going to see the heat continue
01:56or if we're going to see things perhaps turn a little bit more towards average for the time of year.
02:00Nevertheless, though, the temperatures are on the up and not just during the day, but overnight as well.
02:05And we're going to start to see humidity increase too.
02:07So by kind of Monday night, Tuesday night, a chance actually, particularly around London,
02:13that we could see a tropical night.
02:14And that's when temperatures don't drop below 20 degrees for a full 24-hour period.
02:19And if it's quite humid as well, it doesn't make for the most comfortable sleeping,
02:23particularly if you're in the southeast.
02:26But how hot is it actually going to get?
02:28Let's take a look at that.
02:29And we can use our what we call box and whisker plots
02:32to kind of take a look at that over the next couple of weeks.
02:35And we've used these before on lives.
02:38We've used them in quite a few of our videos.
02:40But essentially, the longer the box, so these red boxes are daytime temperatures,
02:45the longer the box, the more spread there is in the models about what exactly that maximum temperature is going to be.
02:51But if the boxes are quite short, there's actually quite a lot of agreement.
02:54So Monday, for example, this is Reading in the south.
02:57We can see on Monday that box is actually quite short.
02:59So temperatures are likely to be in the mid to high 20s.
03:03Then as we head into Tuesday, a bit more spread, a bit more of a longer box.
03:08So still a little bit of uncertainty as to what the exact highest temperature is going to be.
03:12But some models are indicating that we could get kind of 31, 32,
03:16possibly a degree or two higher as we head into Tuesday.
03:19And as I say, that's likely to be the peak of the heat.
03:22And it's not just across the south.
03:24Northern areas as well are set to see an increase in the heat,
03:26perhaps not pushing into 30 degrees,
03:28but certainly the mid to high 20s as we head kind of early into next week.
03:34And then, as I say, from Wednesday onwards,
03:36we see a bit more of a spread in those temperatures.
03:39So a little bit more of a question mark as to how long that heat is going to last.
03:42But certainly Monday, Tuesday and possibly Wednesday,
03:44we're going to see that heat increase.
03:47And the question is, I suppose, why?
03:49Why are we starting to see this kind of return of the heat?
03:53And it's all to do with, well, it's a few things, actually.
03:55It's day-to-day heating, so day by day, obviously the surface, the air is already hot.
04:00And then if the next day is hot again, that just adds to the heat that was already there.
04:04We also have high pressure dominating the weather.
04:07And in a high-pressure situation, generally the air is moving down.
04:10And as it does so, it compresses.
04:12That creates heat as well.
04:14So it's all about subsidence.
04:15So you've got day-to-day heating, you've got subsidence.
04:18And not only that, but by the time we reach Tuesday,
04:21we do actually see a slight change in our wind direction
04:23as we see a shift in where that high pressure sits.
04:26We start to pick up a bit of a southerly, southeasterly wind as well.
04:30So then we start to pick up that quite warm air across Europe.
04:33Obviously, there's heatwave conditions across much of Europe at the moment.
04:37So with that change in wind direction, we're also expecting more heat from Europe too,
04:41particularly on Tuesday, where we are expecting the peak of those temperatures.
04:44So there's a few things going on, which is why temperatures are starting to increase.
04:49But obviously, as I said, for it to be technically a heatwave,
04:52we need to see those hot temperatures over three consecutive days.
04:56So it could be a heatwave or we could just see an increase in the heat.
04:59But nevertheless, it is certainly going to be feeling warm
05:02and many of us are going to be seeing plenty of sunshine.
05:04So I'll see you next time.
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