October 27th, 2025
- Mark Hunt
- 2 hours ago
- 7 min read
Hi All,
Apologies for the absence of a blog last week but I was laid low with illness, can't remember the last time I have had to stay in bed but on the mend now :).
In my absence, the weather has taken a sharp turn towards winter with the muggy high pressure that sat over the U.K and Ireland during mid-October replaced with a strong jet stream, sitting further south and therefore allowing Atlantic low pressure systems to call the shots.
As you can see from this video, my resident Hedgehog has decided that winter is on the way and some extra insulation is required for the home. I put a pile of dry, Beech leaves outside as an incentive and most have gone now. Even the baby Hedgepiglet has been helping out.
Another 'Winter indicator' for me was the appearance of the Grey Wagtail into my garden to pick up Suet sprinkles and Mealworms. Normally it is the first week of November, so this cooler weather has motivated his appearance a week earlier than usual.
I love the colours of the autumn. A walk in the beautiful Fineshades Wood near Corby, accompanied by the odd glimmer of autumnal sunshine showed Mother Nature in its prime. As usual at this time of year, I was also looking for the beautiful Fly Agaric fungi. (Amanita muscaria) It is a fungus that often forms mycorrhizal associations with birch, but also other trees, so the tip (as I learnt from a fellow naturalist - Thanks Clive) is to look for clumps of Birch in the woods. It is of course highly toxic, but I just love the look of it. Find about it on the Woodlands Trust here.
Onto the weather ;
As mentioned above, we have had quite a change in the weather since my last blog two weeks ago. Back then we were sitting under an Omega-blocking high pressure system that was allowing muggy, mild air and almost continual conditions for dew formation. It was also a very high disease pressure period from Microdochium nivale. All change now though....
About the jet stream...
Above is the 10-day projection from the ECMWF model (European Centre for Medium Range Weather Forecasting) and what you can see quite clearly is the very strong pattern in the jet stream (dark green line). Just as a reminder, the jet stream forms between the boundary of warm air (orange and yellow) and cold air (green and blue) and is depicted as a dark green band. When the jet stream is flowing slowly, it forms undulations (like the current in a stream) and when it is strongly, it is less undulating.
The other parameter to observe is the position from a latitudinal perspective, the further south it is sitting, the more likely for our weather (U.K, Ireland, Denmark) to be influenced by the Atlantic weather. The further north is sits, the more likely we are to be influenced by weather form southern Europe.
So if you look at the animated GIF above, we can see a low-lying jet stream and a reasonable flat pattern along its length. This means Atlantic weather is calling the shots for the time-being.
A glimpse across The North Atlantic (pictured above) shows we can see 4 low pressure systems, two higher up level with northern Scotland and two lower down level with The Bay of Biscay. To my mind this sets the scene on the weather for this week with low pressure systems stacking up both for the north of the UK and Ireland and the south. Obviously once they've finished with us, they'll whisk across The North Sea towards Denmark. The animated ECMWF GIF showing precipitation and is shown below for the next 10 days, it is self-explanatory.
So this week, we start the week with that cool north westerly wind in situ, but during the course of Monday it'll swing round, first to westerly and then to south westerly by the end of the day. When we have north westerly winds, it normally means showers pull in from The Mersey estuary and push down across Staffordshire into The Midlands. We will see that today, with heavier rain for the north west and for Scotland, accompanied by strong winds. Further south and west for Ireland, England and Wales, it is likely to be windy with showers rattling across us. Temperature-wise, a little milder than of late because of the change in wind direction. As we progress through the week, we will see the next tranche of rain push across the U.K and Ireland on Wednesday, with potentially more rain for the south of the country. As this low passes through, it'll pull down northerly / north westerly winds from its trailing edge. A small bit of respite on Wednesday before another low pressure rocks up and pushes strong southerly winds and heavy rain across the U.K and Ireland. Currently this low pressure looks to halt its progress west of Ireland and then feed in a steady stream of strong south westerly winds and heavy rain for the end of the week. Denmark will pick up this heavier rain on Friday I think. So strong winds and showers in-between heavier bouts of rainfall during the week.
I think this pattern will continue through the weekend and into the beginning of next week with the first of those more southerly low pressure systems arriving on Monday across the southern half of the U.K, bringing heavy rain and strong winds. That same low pressure looks to then push across The North Sea into Denmark on Tuesday next week.
Remember that an Atlantic low pressure system will always bring its milder south westerly / southerly airstream on its leading edge and as it moves across the U.K, its trailing edge will always be from a northerly / north westerly perspective.
So a typical autumn-type weather pattern with strong winds, gales and rain.
Agronomic Notes
Now for most greenkeepers and groundsman reading the above forecast, it won't be good news. Wet ground conditions make winter projects harder to deliver. They also encourage worm activity, a real pain on parkland courses especially.
The issue as we all know is that we need every drop of our winter rain to replenish reservoir and groundwater levels. Looking at my local Anglian Water website, our main storage reservoirs (Rutland, Grafham, etc) are sitting 68.3% full with groundwater levels rated as below normal. They state that we require more than 100% of the normal rainfall from October through to April for this situation to be reversed.
Now if we look at September using data from The Met Office, the western side of the U.K received the bulk of the rainfall. When you hear companies like Anglian Water quoting phrases like 'more than the normal amount of rainfall' what they are referring to is actually more than the 30-year average rainfall. This is known as the 1991-2020 anomaly. You can find it here for the whole of the U.K on The Met Office website. So the above image shows the distribution of actual rainfall, but if we then compare it to the 1991-2020 anomaly, this is what it looks like ;
To me, this is the more pertinent image because it highlights graphically which areas received less rain than the long-term average. You can see that the middle of the country, the east and some parts of the south east are the areas most affected by the continuing lack of rainfall. This is a two-fold problem because a lot of people live in the areas affected by the continuing drought and a lot of our water reserves are in this area, including some of our largest storage reservoirs for drinking water like Rutland and Grafham.
If you want to drill down on a more local level, The Met Office has a number of regional weather stations that will show the same data. You can find the search page here.
So if I pick Cambridge as a location, I can see the 1991-2020 anomaly data for this location. As an aside, the Cambridge weather station is based at the N.I.A.B, The National Institute of Agricultural Botany, Coincidentally, I spent two very happy years at this institution studying image analysis of cereals and many happy hours thereafter in the institute bar and 'associated activities'. Once I have the anomaly data I can then compare with actual data either from my own weather station or one from The Met Office.
Since we are talking about rainfall, they list the 2025 rainfall to date as 264.6mm vs. the 1991-2020 anomaly for the same time period of 457.54mm, so we are roughly 200mm down or 8" in old money. In my mind that's the additional rain we need to bring us back on track before next spring.
Over the weekend I did a lot of preparation work for a series of talks I am doing this winter and next spring. It is a somewhat boring exercise going through data from time-data series, some of which started in 1665 !!!!. What I was looking for was the propensity for the autumn winter to be drier or wetter than usual.
So here we are talking climate trends and my question was 'What are the climate trends in rainfall for the autumn and winter ?. So I looked for the driest autumn / winter seasons to see if in recent years (post-year 2000) we had experienced dry autumn and winters ? The answer was no. I then looked at the other end of the scale and picked the 10 wettest autumn and winter seasons (I should hasten to add this data was for England-only).
Here is how it looks ;
So as you can see we have only had 2 very wet autumns in the last 10 years, but 3 out of the last 5 winters have been very wet. It is therefore by no means a given that I'll be typing this blog next March with full reservoirs and local groundwater levels back to normal because in reality we need a wet autumn AND a wet winter.
Remember also that we went into this drought with above normal levels of groundwater and reservoirs at full capacity, so it has left a big mark on our water reserves. The bit I don't quite get is if you look at the driest spring and summer seasons since the data series began, sure enough Spring 2025 was the 2nd driest ever for England, but Summer 2025 was only the 28th driest on record. Yet our water reserves are dangerously low ? Maybe because we have a lot more people drawing on those reserves AND of course our present incumbent government ('government' surely a contradiction there) wants to build 1.5 million more of them. Water is becoming a big issue, make no mistake about that.
OK, that's me for another week.
All the best.
Mark Hunt