August 24th, 2026

Hi All,

As we edge into the last week of August, our summer-long drought is coming to an end. Already Scotland, Ireland and the north have received significant rainfall over the last two weeks, but from The Midlands south, we have had painfully little rain so far. If you are old like me you will remember the drought of 1976 ending in the last few days of August and this one is following the same pattern.

There's been winners and losers from a nature point of view.

At my old house in Market Harborough, I have been feeding multiple families of Blackbirds, Great Tits, Greenfinches and Blue Tits this summer. They have run me ragged in terms of keeping the feeder and fat balls topped up, but especially with their constant requirement for water. Now this goes against the advice of the RSPB who suggested ceasing feeding in the summer. I am split on this, but lately I noticed some of the young Blackbirds were unsteady on their feet, becoming swollen and lethargic. The same happened to a couple of Blue Tits. I spoke to Garden Wildlife Health, an excellent organisation that monitors disease and sickness in garden wildlife (find them here - https://www.gardenwildlifehealth.org ). They suggested I stopped feeding, cleaned all my feeders and watering stations (I do this anyway regularly) and let the populations disperse to prevent transmission. It is a tough one but necessary if we are to try and lessen disease levels in our wild bird populations. I think the warm weather has increased pathogen populations so going forward I'll only put out fresh water in the summer.

On the flipside, insects have had it good, lots more Butterflies and Dragonflies around and in the new house I have had 4 Hummingbird-Hawk Moths (image above) fly in for a visit. Insect-feeding birds like Swallows, House Martins and Swifts have had it good as well, though I wonder if they are migrating south earlier because of the state of drought. In fact I think most of our summer migrants have left early.

Maybe they know something we don't ?

When I wrote a couple of weeks ago that we had rain on the way, I mentioned that we needed two key processes to take place to end the drought. The first was the movement of the jet stream to a more southerly position and the second was the passing of the heat plume that has funnelled up from the south to give us so many successive heat waves this summer.

ECMWF projection - Monday 24th August courtesy of tropicaltidbits.com

As you can see from the ECMWF output above, the heat dome has shifted eastwards. This has allowed a low pressure system to position itself initially off Portugal and then later in the Bay of Biscay. It's a BOB and something I haven't written about for a while.

BOB (Bay of Biscay) low pressure systems display two characteristics which are significant for the U.K and particularly the southern half of the U.K.

My Ocean Pro output - marine.copernicus.eu

Firstly, they gather energy from a warm area of sea off the Bay of Biscay. Currently that area is +2.3°C warmer than usual and as you can see from the brilliant output from My Ocean Pro , it is currently 21.97°C. That compares with The Atlantic off Ireland that is sitting at 17.13°C, also +2.3°C warmer than usual.

So that's close on a 5°C difference.

Remember then that for every 1°C rise in air temperature, the atmosphere is able to hold 7% more water vapour. So if a storm tracks up from the south, (if it is a BOB low pressure), it can potentially hold 35% more moisture than one vectoring in from west. The second critical feature of a BOB is that if they swing up to affect the U.K & Ireland, they tend to bring the rainfall to the southern half of the country.

Now, I fully appreciate rainfall for the south has been something of a predicted train arrival that has consistently failed to turn up, but I think this weather signal is much stronger and for the reasons I have detailed, more significant.

What is also significant going forward is the sea water temperature anomaly of +2°C, because as we move into the autumn storm season with one eye nervously glancing at a potentially record-breaking El Niño in The Pacific, it may have grave consequences for storm severity and flooding come the autumn / winter. The last time we had a 'Super El Niño', back in 2015/16, we had an extremely mild winter with near constant flooding and storms. This event is bigger than then, so one to keep an eye on for its effect on our weather this autumn / winter.

With temperatures still in the low twenties it also means that we will have a lot of energy kicking around. Humidity, rainfall and heat means more risk of thunderstorms occurring. Remember then to try lightningmaps.org to monitor those storms if this comes to pass.

Currently, this first significant band of rain is on track to push into Ireland and the southern half of the U.K overnight from Wednesday into Thursday. Now currently the rainfall track is more to the western - central half of the U.K, with less for the east, but don't despair as this is only the first tranch of rainfall. This low pressure will also bring more rainfall through Saturday into Sunday and this will vector west-east. So I am hoping everyone who needs it gets something. OK, it isn't a drought-ender, but it is a positive start.

This enhanced sea temperature may also have an effect on rainfall over Denmark . A few years ago I did a talk to the Danish Greenkeepers Organisation and during that talk I highlighted the biggest risk of heavy rainfall (high rainfall rate events) to Denmark and Jylland in particular was if the rainfall moved up from the south west, along the coast of Holland. This Thursday into Friday, that looks to be the vector, so Jylland, Fyn and Sjaelland may be on the receiving end of some pretty heavy rain at the end of the week.

This week we have high pressure in place for the first half of the week, but as we approach mid-week, the BOB low pressure will push in as described above.

So what's coming next ?

More rainfall or an Indian Summer or both ?

ECMWF 10-day output courtesy of tropicaltidbits.com

After the high pressure system is pushed out of the way, low pressure appears in charge from Wednesday pm through to Saturday / Sunday. Well, no sooner has first BOB low pressure moved out of the way than we see an Atlantic low pressure system push into the gap it has left. This will bring strong, south westerly winds and more rainfall across Ireland and then the U.K from Sunday pm through to Monday pm. As this low pressure moves through, its trailing edge will pull down north westerly winds, so that'll cool things down a little next week. Thereafter, we look to have a week of sunshine and showers, with successive fronts of rain pushing through from the west.

At the end of next week, there's a suggestion of a ridge of high pressure building over the south of England to settle things down again and raise temperatures for the weekend after next. A hint of an Indian Summer ?

I do hope so, as I plan to be Pwllheli-bound and after moving house and receiving some particularly crappy life-curve-balls recently, I desperately need a reset.

Agronomic Notes

Now, it doesn't take a rocket-scientist to figure out that this coming change in the weather will not only bring rainfall but of course an upscaling in humidity and plant leaf wetness. We have already started to see some significant dew events this last week or so. With longer nights, periods of plant leaf wetness will be extended and that means disease pressure will be on the increase.

Smith Kerns Dollar Spot Model - Thame, UK

With some rain showers vectoring south recently, the humidity they brought with them has already nudged up the disease pressure, as we can see above.

Smith Kerns Dollar Spot Model - Galway, Ireland

Regions like Ireland, which had some significant rain recently have seen a bigger nudge up on the Smiths Kern Dollar Spot Probability Model as we can see above.

So, we need to be primed for an increase in disease activity with the arrival of rainfall and humidity. Maybe some Waitea Patch and Fairy Ring this week, with the combination of warmth, humidity and rainfall, followed by a higher risk of Anthracnose, Dollar Spot and Microdochium going forward. Ironically these tend to increase when high pressure is in charge because that's when we get the extended dew events. Working on that principle, the weekend after next is one to watch for now.

The other key point is on re-wetting the ground prior to this rain.

Where do you start ?

Well if budgets and resource allow I would try to apply a soil surfactant to any area I was considering overseeding in the autumn to help it rewet more efficiently prior to renovation work. Easy for me to say / point out, harder to do I know, but it's a thought because a lot of surfaces are hydrophobic and rainwater will initially run straight off rather than rewetting.

OK, that's me done, time to focus on more boxes......and more boxes......repeat ad infinitum :)

All the best.

Mark Hunt