A heatwave across the West Country this week?

What a start to a week in mid-September! A bit of fog around on Monday morning but plenty of sunshine soon developed and temperatures shot up, but are we in for a heatwave this week?

The short answer is no, but only because temperatures will tail off a bit as the week goes on. We recorded highs of 28 °C in Bude on Monday with warm southerly winds due to the position of high and low pressure. Remember, air moves clockwise around areas of high pressure and anticlockwise around low pressure.

Warm air arriving on southerly winds

The last time we saw temperatures near 30 °C in the UK was a ‘rounded’ 30 Celsius with 29.8 °C at Porthmadog, Wales on the 13th August 2020. This came after a stretch of 7 days from 6th to the 12th August when temperatures exceeded the 30 degree mark somewhere in the UK each day.

The highest temperature on record for the UK in September is 35.6 °C at Bawtry, South Yorkshire, 1906, and since digital records began back in 1961 the UK has seen 30 °C or more reached on 6 occasions in September during: 1961, 1973, 1999, 2006, 2013 and 2016.

From Tuesday temperatures will be closer to 23 or 24 Celsius, so still above average by some margin (around 18 °C in September) but below the threshold for heatwave criteria. From the middle of the week the pressure pattern changes and we start to bring in cooler air from the north and northeast.

Cooler air arriving on northerly winds

It won't suddenly cool down though, with temperatures by Friday around 22 degrees. Weather-wise it looks pretty dry too, with some cloud around and just a few showers about. As we haven't had a widespread frost yet it's also not technically an Indian Summer.