October 6th, 2025

Hi All,

Well, September is past and for many it was a wet month following months of below-average rainfall. Here in The Midlands, we remain very dry and the reservoirs I fish are so so low, lower than I have ever seen them.

With October through to March being the time that we hope to refill our streams, rivers and reservoirs and reset our water table for the coming spring summer in 2026, September was a start in that process but we have a long, long way to go. Certainly the North West and Scotland picked up significant rainfall during September with > 220mm for the month (thanks Ben). The South West and the south coast / south east also picked up 100-130mm of rain this past month (thanks Pete), so a wetter month there as well.

Here in The Midlands it was closer to 80-100mm representing 1/4 - 1/3rd of our total rainfall for the year in one month (shows how dry it has been for the rest of the year), with 280-350mm y.t.d typical. There is a belt across the centre of the U.K and extending out to East Anglia which is still extremely dry and needing a lot of rain to set things right.

As I type this, 3 Greenfinches are sitting on the edge of the shallow rectangular plant pot tray that serves as a bathing and drinking area for my garden birds and Hedgehogs. They're thirsty. As you can see above, it is used day and night, with my resident Hedgehog family pictured above. It's a mum and two Hedgepiglets that have taken up residence in my garden and boy do they bicker. It isn't the whole Hedgehog story though as there are other miscellaneous ones either living or visiting. I love to watch them. The other night, the mum (presumably) was picking up clumps of leaves in her mouth and dragging them into the Hedgehog house, shoring it up for the winter. The risk at this time of year is that the last brood of Hedgehogs is often produced very late into the autumn and then the parents go into hibernation before the youngsters have been weaned. You then see youngsters under-nourished and ill, wandering around in the day, a sure sign that they need help and a visit to your local animal sanctuary.

For the second year running September has been a wet month for many. I find this strange as it used to be a month associated with stable, high pressure systems providing warm, autumnal sunshine and cooler nights. Now it looks like October is going to pick up that particular mantle. So after Storm Amy marked a turbulent start to October, what is the prospect for more rainfall in the next few weeks?

10-day GFS Outlook provided by tropicaltidbits.com

Well, the GFS outlook indicates that rainfall will not be a feature of the first half of October by my reckoning (of course it could easily change). The jet stream has lifted north and this will allow high pressure to form into an Omega Blocking Event (Ω) over the UK and Scandinavia later this week. The consequence of an Omega blocking event is that low pressure systems coming in from The Atlantic get pushed over the top of the 'heat dome' and into Central and Eastern Europe, so the outlook is dry.

So for this week we will see a period of adjustment after Storm Amy pushed across the country over the weekend and then crossed The North Sea into Denmark. A consequence of this movement into Scandinavia is that Denmark will start wet this week before the effects of the Omega block stabilise the weather and things settle down. For the U.K & Ireland, we will see the same pattern, with rain pushing in from The Atlantic to affect the west and north west of Scotland and Ireland during Monday and Tuesday. As we progress through the week and the high pressure system builds, then this rain will increasingly become isolated to north west coasts before becoming drier at the end of the week. Moving south to England and Wales, we will see a dry week but not necessarily a hot week.

This is because the position of the high pressure is to the west of the U.K, sitting just off Co. Kerry which means its leading edge will dictate the wind direction. High pressure systems rotate clockwise and so the leading edge of a high pressure will pull down a northerly airstream or in this case, a north westerly airstream. So it will be warmer at the start of this week before the influence of the high pressure asserts itself with temperatures tipping into the low twenties initially before dropping back to the mid to high teens for England, Ireland and Wales, slightly higher for Scotland and slightly lower for Denmark. I think it may then get warmer next weekend as the high moves directly over the U.K and we lose that cooler wind direction and strength.

Either way, dry, warm (ish) and settled once the rain moves away from the north / north west and Scandinavia is the current outlook.

Agronomic Notes

Ordinarily at this time of year, an Omega blocking event, with a high pressure system sitting under it usually sets off alarm bells as I would associate it with disease whether that be Microdochium, Dollar Spot and / or Anthracnose. So is this a threatening prospect for this and maybe next week ? (because it could last for the first half of the October)

Well possibly, but it is a complicated dynamic and tough to call.

Let's break it down into phases with the date shown top right ;

So, initially this week we start with a westerly to south westerly airstream which means it'll be mild and humid before the high pressure begins to develop. Definitely a risk of foliar disease for the U.K, Ireland and Denmark.

During the 2nd half of the week we have this north western airstream in place and that'll be a cooling one, so both day and night temperatures will dip taking it below the activity zone for Dollar Spot, but still in the sweet spot for Microdochium.

By the start of next week, the position of the high pressure system has shifted north and east and so that means a change in both the wind strength and direction. By this time we are picking up wind from the trailing edge of the high pressure and so if you look at the GIF above it means a predominantly south easterly airstream for the U.K and Ireland (vs. very little wind at all for Denmark). Now at this time of year, a wind flow from the SE means warm, humid air, so I think there's a higher risk of more disease activity from the weekend onwards as the wind direction first falters and then changes to SE.

It means in my books significant dew formation for the duration of this weather system and that again should set some alarm bells off because plant leaf wetness combined with potentially warm overnight temperatures means a heightened disease risk.

So, if we are talking specific mitigation strategies, obviously this isn't my bag anymore in terms of product type / formulation, but I can still handle generalities. Point of fact, you should know by now what you are happy with in terms of discouraging disease development whether that be using a hardener formulation (or mix), physical removal (rolling for example which would suit this run of weather being dry) and / or a dew control. The latter to me would be more advantageous towards the end of this week as winds drop and the potential for a longer dew duration increases.

As an aside, the reason for this is that the trend towards lighter winds associated with high pressure systems decrease the mixing of cooler air near the ground and warmer air above it. (warm air rises of course) the net effect is that a layer of cooler air develops above the ground. In this layer, the air temperature is closer to the dewpoint temperature (the point at which water vapour transforms from a gas to a liquid) and so dew (and mist / fog above ground) is more likely to form. Either way, I'd set out my stall in terms of mitigation strategies, you have due notice after all.

I'd also be looking at the forward disease modelling apps / programs because for a high pressure system, the weather forecast accuracy increases and so therefore does the probability of correctly forecasting disease.

OK, short blog this week, enjoy the autumnal temperatures, I'm off to attend my first RMets lecture (Royal Meteorological Society) on summer thunderstorm development and forecasting, where I am sure to be hopelessly out of my depth sitting next to 'proper meteorologists', but I'll try to blend in and nod at the appropriate point before considering the salient points on the long drive home 🙄

All the best.

Mark Hunt