There’s a lot of talk at the moment about the possibilities of tomorrows Bank Holiday being the warmest on record. Call me an old stick-in-the-mud traditionalist if you want, but I like to think of the early May bank holiday as being linked to the pagan holiday of May Day, which tradition has it falls on the very first day of the month for some obscure reason, and not the first Monday as it does now. I could write some code to list the warmest, but to hell with that, I thought it was much quicker just to look at warmest May Day’s rather than the warmest Bank Holiday which flits around from year to year. Anyway looking at maximum temperature in Central England it looks like the warmest since 1878 was back in 1966 with a temperature of 23.7°C which was almost 10.2°C above the 1961-1990 long-term average (fig 1).
The synoptic situation back in 1966 was not that different from the one at the moment (6th May 2018), with high pressure to the east and a col over western areas (fig 2). Why back then in SYNOP reports we rounded temperatures to the nearest whole degree and reported pressure to tenths of millibars now looks rather odd, even allowing for low power communication speeds with Baud rates of less than 9600 (fig 3).
Looking back at the warmest May Day mean temperature since 1878 in Central England, 1990 and 2005 with 16.1°C tie for the honours for that (figs 4 & 5).