I may have to crack out the shorts next week for work. My written rule is that anything over 16C / 61F is typically shorts and t-shirt weather in my line of work. Otherwise I will overheat if I am working in jeans and a hoodie inside the warehouse. Those forecasted nighttime temperatures are ridiculous as well for 51N during the last week of December. I would expect nighttime lows of 13-14C in July, let alone late December. Some model runs are putting the nighttime lows at 15C for Wednesday and Thursday following a high of 18C / 64F on Wednesday!
14C at 850hPa translates to about 17-18C at ground level. It will be interesting to see just how warm it gets, especially if some eastern places also benefit from a Foehn effect too. Potentially 20C / 68F in a few eastern locations, although I find that hard to believe during the last week of December at 51-54N. Probably 18C maximum. If we had a setup like this in July it would bring 35C+ temperatures.
The consistency of the ensemble runs is remarkable! I have never seen a set of ensemble runs so consistent like this. It looks like this warm/mild spell is nailed on now.
Here's the ECMWF for Wednesday, which is supposedly going to be the warmest day, although it could be any of Wednesday, Thursday or Friday in theory.
UKMET pumping higher pressure and warm air up from Africa, although the airflow into western Europe and the UK is coming up from the Canary islands specifically.
The GFS model puts Jan 1st / New Years day as the warmest day potentially...
Here's the ECMWF model for New Years day. Both setups looking very similar. Potentially record breaking in many places on the western half of the continent.
December records, and possibly winter records too, may tumble next week in Spain, UK, France, Netherlands, Germany etc. Watch this space. Daytime maxima and nighttime minima both at threat.
Of the the three major humid subtropical regions of the World:
The southeastern United States
East Asia (central and southern China, southern Japan, etc)
The Pampas of South America (northern Argentina, far southern Brazil, Paraguay, and Uruguay)
The last one listed is the least affected by severe cold waves and is also favored biologically since it is contiguous with the Neotropics.
Even so, I am mildly surprised that the subtropical latitudes of South America are not immune to moderately low temperatures, even brief freezes.
For instance, at the end of June 2021, a cold snap brought temperatures down to 0.8C at Asuncion and -1 at the airport near Iguazu Falls at the northern tip of Argentina.
Both locations are inland, away from the coast, but at about the same distance from the equator as Miami, Florida. All time record lows for these places would be around 25F/-4C so I would say that the temps experienced a couple of weeks ago are worthy of note.
The recent cold appears to be somewhat localized because Porto Alegre, Brazil at 30S latitude, but very close to the Atlantic, got no lower than 5C, even though they had cold rain with a high temp of only 10C on the last day of June.
Even Buenos Aires, some distance to the south, comparable in latitude to Little Rock or Osaka bottomed out at around 3C. Earlier in the season, B.A. fell to about 1.6C and that is the lowest they've seen this winter so far.
Like the southern United States, the coldest temperatures of the winter season in warm temperate parts of South America typically occur around or just after the solstice and less so during latter part of the season.
In East Asia by contrast, February is usually the coldest month.
La Nina patterns or cooler equatorial sea surface temps from the Central Pacific through to the Easter Tropical Pacific are occurring right now. These patterns often lead to dry and clear Autumn and Winter weather patterns here in Southern California where I live. The west coast just experienced a typical La Nina weather pattern last weekend with an inside slider storm coming down the coast with strong winds and leaving us now with cool dry nights and no marine layer. I hope that this isn't a sign of what is to come as we get deeper into Autumn and enter Winter. With clear skies, I bottomed out at 39 degrees last night, and even the weather station at Moonlight Beach right on the ocean was reading 43 degrees this morning at first glow.
The leaves on my banana plants got pretty beat up, and the Encephalartos laurentiaunus below which is flushing had some leaflets ripped off in the strong winds. Everything below the wall was protected, while everything above the wall felt the full force of the wind.
So how are you and your garden doing this during this La Nina Autumn?
What exactly are sunset climate zones? I tried to look it up and basically every site just says, "it takes in all the factors of growing in a climate" and then doesn't really explain it. Is a higher number good or bad? What's the scale?
By John in Andalucia
This site has given me a better understanding of average temperatures for highland species. I think it's a great resource for palm growers.