The calendar said autumn. The thermometer, apparently, did not get the memo. De Bilt reached 20 degrees or more on each of the first five days of October, straight after a September that bowed out with two heat records in a row.
Some perspective: in a normal October, De Bilt manages about two days of 20 degrees or more. In the whole month. This year it had used up that allowance by 2 October and simply kept going: 22.0 degrees on the 1st, then 20.4, 20.9, 20.3 and 21.4. The usual early-October high is around 16 degrees, the temperature at which a sensible person reaches for a scarf.
The warm-up act started in late September. On the 29th De Bilt hit 25.9 degrees, toppling a record that had stood since 1934. The next day it beat the 1975 record of 24.3 degrees for good measure, while the east of the country went past 27. Weeronline counted it as the 13th date record of the year. At this rate the record books will need a second volume.
September as a whole averaged 16.7 degrees, two above normal and the fifth-warmest on record, with 20 days of 20 degrees or more where fewer than 12 is usual. And it arrived fresh from the warmest summer since measurements began in 1901: 19.3 degrees on average, nudging 2018 and its 18.9 into second place.
So who is to blame? The obvious suspect is El Niño, and it certainly has form: a very strong one is building in the Pacific right now. Unfortunately for a good story, it has an alibi. According to KNMI, its influence on Dutch weather is very small. The real culprit was closer to home: a southerly wind that shipped in warm air from southern Europe, free of charge. Its accomplice is a warmer climate, in which, Weeronline notes, the same weather pattern now simply delivers more degrees than it used to. This century the score stands at nine heat records for every cold one.
The result was a country of mixed signals: T-shirts on the terrace, autumn leaves in the cappuccino. The weekend of 3 and 4 October brought sunshine and around 20 degrees once more, and café owners kept the chairs out a little longer.
By the time you read this, the leftovers should be gone. The forecast had the wind picking up from Wednesday 7 October, with showers and a maximum of about 16 degrees. A normal October day, at last. Time to take the jacket off the back of the chair and put it on.