London winter forecast 2019/20

For this year’s winter forecast, because of time constraints, I am sticking purely to what the local analogues reveal.

Meteorological autumn was the wettest for 18 years and the coolest for 6 years, revealing some interesting similarities with past climate. Considering data back to 1797 I was able to make the following suggestions on how the next 90 days may unfold.

December is most likely to be on the cold side with rainfall slightly below average.

January is most likely to finish average temperature-wise and wetter than December.

London’s February extremes temperature also look average overall and the precipitation signal also creeps up in comparison to the first two winter months.

Best chance for snow? Impossible to pin down but the coldest weather is likely to be at the beginning of February, the third week of January and just after Christmas.

The warmest period looks to be around January 10th while there’s also a signal for that often phenomena of milder temperatures just before Christmas day.

Most of the probabilities in the above statements are relatively low and are explained in the table below.

Mean temperature 2019/20

December		January		February
1981-2010 average	5.6	1981-2010 average	5.3	1981-2010 average	5.3
Forecast median	4.4	Forecast median	4.7	Forecast median	5

Rather cold	40%	Normal	40%	Normal	44%
Normal	28%	Rather cold	32%	Rather cold	32%
Mild	20%	Very cold	12%	Mild	16%
Cold	4%	Mild	12%	Cold	4%
Very cold	8%	Cold	4%	Very cold	4%

Rainfall 2019/20

December		January		February
1981-2010 average	53.2mm	1981-2010 average	55mm	1981-2010 average	40.1mm
Forecast median	48.3mm	Forecast median	55mm	Forecast median	40mm

Wet	32%	Wet	32%	Wet	36%
Normal	20%	Normal	28%	Normal	36%
Dry	48%	Dry	36%	Dry	28%