Heatwave comes to an end in the Channel Islands

Photo at St Ouen's Bay taken by Elizabeth Longbottom
Photo of September sunset at St Ouen Credit: Elizabeth Longbottom

The heatwave is officially over in Jersey!

This will either fill you with joy if you found it too hot, as the schools headed back after the summer break or disappointment if you revelled in outdoor and beach activities that many longed for in July and August.

It was the first summer the country didn't reach 30C - which is quite a difference to last year's heat!

How hot did it get last week?

Over five consecutive days last week the temperature rose above 28.0C - culminating in the hottest day of the year on Saturday 9 September in Jersey and Guernsey which saw 31.2C and 29.5C respectively.

Alderney had its highest temperature of the year on both 7 and 8 September with 27.1C.

Even though it was hot in Guernsey and Alderney, temperatures reached the mid to high twenties in Celsius, but it didn't meet heatwave criteria where there needs to be a period of at least three consecutive days where the air temperature reaches 28.0C or more.

Are the warm nights going to get cooler?

Yes, it should start to get easier to sleep after the uncomfortable humid nights we've had recently.

The first tropical night of the year was recorded on 6 September - where the minimum temperature was 20.2C.

Normally temperatures as high as that are experienced during the daytime.

Thankfully for many yearning for cooler nights, there should be a noticeable difference in overnight temperatures this week back to mid-teens - which will feel much more manageable for a good night's sleep - no fan required!

Have there been record-breaking temperatures this September?

No, not quite.

The warmest September temperature for Jersey was in 1906 on the first of the month at 33.3C.

For Guernsey, it was on the second of the month in 1961 with 30.6C.

There have been 12 occasions where the temperature has been above 30C in Jersey in September since records began in 1894 at the MSL Observatory.

These occasions are:

  • 9/9/1895 30.0C

  • 8/9/1898 30.1C

  • 1/9/1906 33.3C

  • 4/9/1911 30.3C

  • 7/9/1911 32.9C

  • 8/9/1911 32.8C

  • 4/9/1929 30.1C

  • 4/9/1949 31.7C

  • 2/9/1961 31.0C

  • 14/9/2020 30.8C

  • 7/9/2021 30.0C

  • 9/9/2023 31.2

So it's back to temperatures being in the low twenties this week for the Channel Islands - about average for the time of year - possibly a touch above - but with plenty of sunshine to be enjoyed.

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