This thread is for all comments, discussion, and analysis of temperatures in the UK during March, with particular emphasis on the Central England Temperature (CET), for the simple reason that it is the longest-running temperature series in the world with over 360 years of data. But you can comment on any interesting temperature statistics or data from across the UK, including your own backyard. 

For those taking part in the competition, all CET predictions for March should be sent directly to me via the forum private message system. Please do not post them directly into the thread.  

Historic CET summary for April 

1981-2010 8.52C (30 years)  

1991-2020 8.95C (30 years)  

2001-2020 9.14C (last 20 years)  

The last four April's have all been well above average (compared to 1971-2000). Last year we reached 10.4C. We have exceeded 10C in April no less than 5 times since 2007. There have been hardly any cold April's since 1990. We did have a few in 2012, 2013 and 2016 when the CET was between 7.2C and 7.5C. April is one of the months where the average CET has increased massively over the last few years. The April CET for 2001-2020 is more than 1C above the 1971-2000 mean of 8.07C.

Here is a chart of the April CET for all years since 1961 

Direct link to a larger version of the chart

Current model output   

850s start the month above average but quickly turn colder from 5th to the 12th. There is a signal for warmer conditions from mid-month with perhaps something cooler again towards the end of the month.

GEFS 850s 

https://www.wetterzentrale.de/de/show_diagrams.php?geoid=49069&model=gfs&var=2&run=99&lid=ENS&bw=1

https://www.wetterzentrale.de/de/show_diagrams.php?geoid=49069&model=gfs&var=5&run=99&lid=ENS&bw=1

ECM (de Billt) looks to be similar to GFS with temperatures likely to be well below average from the 2nd to the 12th. By the end of the run signs of something warmer which is consistent with what the GFS is showing.

http://cdn.knmi.nl/knmi/map/page/weer/waarschuwingen_verwachtingen/ensemble/detail/ensemble-verwachtingen-detail10.png

Met Office contingency planners outlook 

I seem to have difficulty displaying the pdf document on the web page in Safari. The best thing to do is download it and then open the file outside of Safari.

https://www.metoffice.gov.uk/binaries/content/assets/metofficegovuk/pdf/business/public-sector/civil-contingency/3moutlook-amj-v2.pdf

The 3-month outlook is a 35% chance of warmer than average conditions (which is 1.8x normal). Cooler conditions are 0.5x normal probability.

Increased chance of high pressure extending into the UK from the west and south-west during April. This means an increased chance of warm and dry conditions (and an increased chance of wildfires!). Brief cold spells with transient snow are also possible though!

Met Office Hadley         8.8c         Anomaly        1.9c. Provisional to 1st.

Metcheck                      6.66c       Anomaly        -1.36c

Netweather                   8.54c       Anomaly        0.45c

Peasedown St John      8.14c       Anomaly       0.26c.  

Met Office Hadley         7.8c        Anomaly       1.1c provisional to2nd

Metcheck                      6.49c      Anomaly       -1.53c

Netweather                   7.6c        Anomaly       -0.5c

Peasedown St John     7.9c       Anomaly        -0.5    

It's interesting that the two biggest April snowfalls I can remember (1981 and 2008) were in months that were only slightly below average. Plenty of other cold Aprils were comparitively snowless.

I always think of April as the month of all seasons in one day!  

I remember one Easter Sunday, possibly 2008, building a snowman in the morning and then sitting in the warm sun in the afternoon with all the snow gone except the snowman.  The rest of the week was was warm and sunny. 

First look at the April CET tracker. A cold first half of the month.

Only 6.69C by the 17th. That's 0.5C colder than the March CET. However, we only have to go back to 2019 to find another April that had a similarly cold first half.

Chart 1

Chart 2

Here is the list of April predictions

Table

Well, looking at this morning's output from the GFS, its tempting to think that the vast majority of us have gone too high.

If that run (0z)  is anything like close to being accurate, then I will be banking on a considerably warmer second half of the month.

Things will show a different perspective on the next run I would imagine.

Meanwhile, thanks GW for the all the charts and for continuing to run this great competition.

Met Office Hadley          7.5c          Anomaly         1.0c provisional to 3rd

Metcheck                       6.10c        Anomaly          -1.92c

Netweather                    7.23c        Anomaly          -0.88c

Peasedown St John      7.1c         Anomaly          -1.3c. 

Not necessarily. The first half could certainly be very cold, but don't disregard how much a late April warm spell could lift the CET up, especially if it comes with mild nights too. It is the most rapidly-warming month of the year after all.

Well then. That makes the 3rd month out of 4 so far this year that I've been surprised by the spread of predictions!

I suppose a lot of you either expect the cold spell to be majorly downgraded - especially by night - or be followed by a considerable run of warmer than average conditions.

My take is, the overnight lows will be the kicker this month. The pattern is ripe for numerous nights falling 2-4 °C below zero widely.

Even last night, with mild air aloft, Pershore dropped to -3.6°C (then climbed to 17.9°C today, an impressive hike!).

At times next week, we'll have exceptionally cold air in place and light winds, so unless there's a lot of cloud, the plants and young animals are sadly in for a very difficult time.

The main uncertainty factor for me is GFS' handling of temperatures in spring, which seems to be the season that it struggles with most in England. Most likely, it's undercooking daytime temps by 1-3°C, but by night there's more of a spread around the actual, tending to go too cold when it's breezy or low cloud develops, but not cold enough when winds are light and skies stay clear.

Met Office Hadley         7.3c        Anomaly        0.9c provisional to 4th

Metcheck                      6.73c      Anomaly        -1.29c

Netweather                   7.25c      Anomaly        -0.86c

Peasedown St John      6.97c     Anomaly        -1.43c. 

https://twitter.com/peacockreports/status/1379162245112946693

As visualised here, the GFS 12z is an explicit run with the lowest overall temperatures to have been observed in any historical year with a CET to 4th within 2°C of 2021's provisional figure.

Two-thirds of the way through the month, it has the CET anomaly below -3°C. If conditions were then bang-on average for the remainder of the month, the final CET would be in the mid-6s °C, over 2°C below normal and around a degree below splinter's table-footing 7.4°C prediction! 

Thankfully, there are plenty of less cold model runs to be found. No ignoring that resilient negative NAO tendency, though.

The statistical projection will be interesting to revisit a week from now... 

Met Office Hadley         6.8c       Anomaly    0.4c provisional to 5th

Metcheck                      6.03c     Anomaly     -1.99c

Netweather                   6.88c     Anomaly    -1.23c

Peasedown St John     7.4c       Anomaly     -1.0c.        

Met Office Hadley        6.2c.      Anomaly      - 0.3c  provisional to 6th

Metcheck                     5.38c     Anomaly       -2.63c

Netweather                  6.12c     Anomaly       -1.99c

Peasedown St John     6.4c      Anomaly       -2.0c.            

Such a chill Spring here.

Mean monthly temperature so far this month stands at just 5.7c.

Cold compared to the January mean this year of 4.5c, Feb 5.7c and March 7.2c.

Current CET tracker showing just 6.60C by the 21st.

CET bottoming out today at 5.23C. After a small rise in the next couple of days, it bottoms out again at 5.23C next Monday.

The first half of April is predicted to come in at 5.63C.

We could be looking at the coldest first half of April since 1986. Coldest 1-15 April periods in recent years:

1986  4.37C
2000  5.62C
2013  5.77C
1994  5.79C

Chart 1

Chart 2

Met Office Hadley        5.8c      Anomaly       -0.7c provisional to 7th

Metcheck                     5.29c    Anomaly        -2.73c

Netweather                  5.67c    Anomaly        -2.44c

Peasedown St John     6.2c      Anomaly       -2.2c. 

Finally seeing some signs of warmer weather for next week, albeit only reaching near-average for the most part.

Gives me an estimate of 6.1°C to 21st but that's assuming GFS is right to drop the night temps so low 10th-12th (subzero, as low as -3°C) which takes my rough estimate down to 4.9°C, a bit below GW's. It also includes a brief cold spell 19th-21st that brings two more frosty nights.

An average remainder of the month would then give us a final CET in the low to mid-7s °C.

Generally, there are signs of a pattern shift toward one more supportive of UK/Europe centred ridges, but also of continued extensive high-latitude blocking, which poses a risk of further unusually chilly interludes later in the month.

I'm starting to sense the possibility of some pleasantly warm weather in the final week of the month, though. If fact, there's some good momentum building toward a fine May this year as the La Nina event gets eroded away by powerful tropical waves in the Pacific. Hopefully that will hold!

Met Office Hadley         5.9c       Anomaly      -0.6c provisional to 8th

Metcheck                      5.59c      Anomaly      -2.43c

Netweather                   5.92c      Anomaly      -2.19c

Peasedown St John     6.2c       Anomaly       -2.2c. 

Met Office Hadley       6.0c.      Anomaly        -0.5c provisional to 9th

Netweather                 5.55c     Anomaly        -2.46c

Netweather                 6.08c     Anomaly        -2.03c

Peasedown St John    6.36c     Anomaly       -2.04c 

Met Office Hadley          5.8c        Anomaly      -0.7c provisional to 10th

Metcheck                       5.34c      Anomaly      -2.68c

Netweather                    5.94c      Anomaly      -2.17c

Peasedown St John      5.23c      Anomaly      -3.17c.