February 24th, 2025
Hi All,
A taste of spring at the end of last week and over the first part of the weekend with temperatures rising into the mid-teens, but it ended on a very wet note for Wales in particular. A Davis weather stations in Cardiff showed 59.2mm of rain falling yesterday peaking at a maximum rain rate of 31.2 mm per hour at 16:12pm. Once again the trend of today's climate for high daily rainfall totals accompanied by heavy-violent rain rates is an ever-present feature of our weather. By the start of next weekend we are tip-toeing into March, so it is high time we saw an uplift in temperature.
On a personal note, to see some sunshine and feel the warmth in the air was such a tonic after what feels like a very long drag of a winter with below average temperatures and sunlight.
Now, March 1st is the start of meteorological spring, so what's the outlook look like ?
General Weather Situation - w/c 24-02-2025
If you look at the animated GIF above you can see the dark green band that typifies the location / path of the jet stream at the boundary between cold and warm air.
For the majority of the week, it is situated below the UK & Ireland which means colder air can push in and that's what we will see this week. For people on the receiving end of last weekend's very wet weather, there is some respite in the forecast as high pressure looks to build. At the same time, the jet stream moves northerly by the end of next weekend and that allows warmer, drier air to push up for the start of next week.
The forecast for this week splits neatly into two. From Monday to Wednesday we have a south west / westerly wind in situ and that will push rain across the U.K, Ireland and Denmark at the start of the week. That wind will remain strong to blustery as well and temperatures will dip below double figures from Tuesday onwards. Sunshine and showers will be the outlook on Tuesday before a weak low pressure system passes over Ireland and the southern half of the U.K on Wednesday bringing rain to many areas though I think it will pass south of Denmark later in the day. As I have discussed before, the trailing edge of a winter low pressure system pulls down cooler, northerly air and this means the second half of the week will be cooler with night temperatures close to zero, meaning a return to night time frosts. So the second part of the week will be drier as will the weekend (mainly) aside from an Atlantic weather front that will push rain into the west, north west of Ireland and west of Scotland overnight into Saturday before fizzling out.
Weather Outlook - w/c 03-03-25
So next week looks much better than this week really if you are looking for some respite from the rain as high pressure is projected to build from Sunday onwards.
Now, there is a caveat here because we have some very active Atlantic fronts and one of these could easily push that jet stream further south and negate this forecast.
For now though it looks like we will be on the dry side, staying cool for the start of March I think with temperatures reluctantly nudging into double figures for the early part of the week and maybe some nice sunshine as well. Now currently high pressure looks to hold the fort for the first 10 days of March as an Omega blocking event takes shape, so that means cool, dry and settled I think, maybe some periods of milder weather, but still not entirely great growing weather. A lot can change in this forecast so we will see next week if it wins the day or those Atlantic fronts prevent the blocking event from forming.
Agronomic Notes
Last week, I charted out the cumulative GDD (Using 6°C base temp) from our default location @ The Oxfordshire in Thame, U.K and predicted a nice bit of uplift at the end of the month using projected daily temperatures provided by Meteoblue. Interestingly it was accurate to 1GDD, so a tip of the hat to them as a weather company :).
The total projected GDD by the end of February 2025 is 43GDD from Jan 1st to the 28th February using 6°C base temp. I have added to the chart when we passed that same GDD totals in recent years and you can see how far behind we are growth-wise vs. 2024, 2023 and 2022.
Just thought, I'd also chuck in some other locations across the U.K, Ireland and Denmark so you can see the variation in GDD circa cumulative Jan 1st - 23rd February, 2025.
Again I am using the 6°C base temperature as a basis for the GDD calculations....
Location Cumulative GDD total (as of 24th February, 2024)
Glasgow 37.7
Fife 21.4
Scarborough 26.1
Southport 33.1
Sligo (Ire) 60.4
Limerick (Ire) 93.4
Crossmaglen (Ire) 23.2
Sutton Coldfield 30.8
Bury St Edmunds 35.4
Milton Keynes 23.3
Thame 36.0
North London 19.9
Sevenoaks 34.3
Guildford 37.8
Winchester 33.2
Bath 32.7
Barnstaple 60.2
Honiton 28.6
Silkeborg (Den) 5.10
Horsens (Den) 2.90
Some big differences across these locations unsurprisingly when you consider the geographical variation across the subset I covered, from Denmark where we can see how much colder (less GDD) they have accumulated vs. the west coast of Ireland, which has been closer to the temperate high pressure systems pushing in from The Atlantic. Amazing really.
Uplift in soil temperature....
It wasn't just the air temperature that picked up at the end of last week. The combination of mild air and rainfall meant that the soil temperature reacted very quickly as well. Warm rain soaking into the ground soon increased the soil temperature from just above freezing on the 19th of February (pretty much where it had been all month really) to a peak of 9.9°C @ 14:30pm on the 21st of February. Since then it dropped back a little as more rain, now a little cooler influenced the readings.
Those who have overseeded early as part of aeration will see a benefit from this but it won't be immediate because I expect soil temperatures to drop back at the end of this week. We have to remember it is still early in the year and as we can see from the GDD, 2025 has kicked off as a cool one in most locations. Time to be patient.
OK, that's me for another week, all the best to you...
Mark Hunt
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