John Hammond’s Month Ahead – Heatwave’s coming. How long will it last?

The days are getting shorter! A relentless slide into autumnal weather? Far from it! Regular readers of my blog will be aware that I’ve dismissed premature rumours of a heatwave . But this time around – love it or hate it – the heat is heading our way.

Heatwave arrives next week

Dry spell lasts until the end of the month

Thunderstorms threaten through early July


Sweltering temperatures

As the jet stream is deflected away far to our north, a large dome of high pressure is building from the Atlantic into northwest Europe. Three things will conspire to send temperatures soaring across the UK, bringing the hottest spell of the summer so far:

  • Heating from below. Clear skies will allow relentless sun to ‘bake’ the ground.
  • Heating from above. Air will descend, compress and warm up through the atmosphere.
  • Heating from the Continent. A subtle shift in winds will bring air from hot land rather than cool ocean.

So I expect a steady rise in the mercury through the early part of the week, reaching the mid- to high-twenties quite widely; and possibly the low 30s Celsius in some spots by midweek. At this range, I also expect some weather apps will underestimate the peak temperatures later next week.

The sun is at its strongest now; so check out Sara’s great blog on staying safe in the sun.

The heat doesn’t suit us all of course. With light winds, one feature of this week will be how stifling it may feel for some by day, with some warm nights to endure. And of course, for hay-fever sufferers, there’s no quick end in sight to the high pollen counts. Sara has written another great blog about the trials and tribulations for hay-fever sufferers.

Whatever your outdoor pursuit, stay safe but have fun! There’s so much going on. For example, in the build up to the ‘big one’, there’s plenty of tennis to enjoy. And I envisage no interruptions to the Boodles at Stoke Park.

There are hints in some computer models that a few thunderstorms may develop by the weekend, but these look quite isolated to me. The dry and hot weather looks set to last until the end of the month.

…some weather apps will underestimate the peak temperatures later next week


Rumbles in the distance

Computer models begin to bring us conflicting signals as July begins. Some of these allow cooler air to arrive from the northeast. Others bring a thundery breakdown, then fresher conditions, from the west.

But my hunch is that the dry and warm story may prevail across many areas through much of next week. Of course after such a long dry spell, concerns are rising about water shortages. Well, your lawn may suffer; but after a wet spring, there are no immediate concerns yet regarding water supplies more generally.

The lawns at Wimbledon will get some artificial help of course. There may be the odd interruption at SW19, but the covers won’t be on for long. In another part of southwest London, at the Hampton Court Flower Show, the blooms should be at their dazzling best. And just up the Thames, it’ll be thirsty work for rowers and spectators during the Henley Regatta. Rehydration will no doubt come in many forms…

By the weekend of the British Grand Prix at Silverstone, there’s an increasing chance of rain clouds looming. Wet or dry, the weather is bound to be a key element before the chequered flag is raised.


A change of tune?

As I’ve said in previous blogs, rumours of a long and hot summer look premature to me. It’s increasingly likely that the jet stream will eventually begin to burst our bubble of warm and dry weather through July, although just how this happens is very unclear. No good hot spell is complete without a thunderstorm of course; and with so much heat stored up in the atmosphere, these could be quite severe.

But eventually I expect fresher Atlantic air to sweep the heat and humidity away. And as low pressure takes centre-stage, albeit temporarily, there could be quite a lot of rain. That’ll be good news for the gardens; but event organisers, participants and spectators will be tensely looking to the skies. There are so many music festivals to enjoy through July – BST, Latitude and, later, the Green Man Festival – to name just a few. Hardy festival-goers will know better than to dismiss the chance of the odd downpour. But at this stage I don’t expect the deluges to be too disruptive.

Of course there are few sports more affected by the elements than golf. And The Open at Carnoustie will be no exception. If the wind blows like it can do across this famous old links course, then perhaps there’s a better chance of a weather-hardened Brit winning! Let’s hope so.

By the end of next week the heatwave will be in full swing. As I wipe the sweat from my brow and sit down to write my update, I’ll have a clearer idea of just how long it will last! With the school holidays approaching, I’m aware that the pressure’s on!

To ensure you are reading John’s very latest month-ahead blog and to look back to previous ones, check out Wow and Why

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