Summer (June, July and August) this year was significantly cooler than last year's (especially July), but fairly close to the long-term average for Southampton Weather Centre (1981-2010). It was much wetter than summer 2018 with June and August significantly wetter than the long-term average.
|Average Tmax||Average Tmin||Precipitaton|
|Southampton average 1981 - 2010||20.2C||22.4||22.3||11.7||13.7||13.7||50.4||42.0||50.4|
Notable days and events
The highest temperature of the summer was on 27 August when it reached 30.5C. This was the only occasion when the temperature was higher than 30C ("tropical") compared with six days in 2018. The coldest temperature of the summer was 6.1C in June.
It rained (more than 0.5mm) on 30 days this summer (out of 92) and we had a wash-out (of more than 10mm rain) on eight of them. A total of 38.2mm rain fell on 7 June, the wettest day of the summer.
On 7 June, Storm Miguel (a typical Atlantic cyclone) threw fronts and troughs over us to give a total of 38.2mm rain. It was raining when I woke, having started around 5am, and it stopped about midday before starting again in the early evening. Remarkably, the ground simply soaked it all up. There were only small puddles on the road and it was dry between the two main pulses of rain, as soon as the sun came out. This storm sparked thunderstorms to our West and North but they missed us.
We saw spectacular thunderstorms on 24 July, moving from France in very hot air. A first wave arrived around midnight. These storms were relatively high-based, so we saw genuinely continuous lightning and rumbling thunder all over the sky, clearly moving from the south to the north, but with very few "thunderclaps". I saw no cloud to ground lightning. After about an hour, we had a band of slightly less active lower-based thunderstorms, with a mixture of cloud-cloud and cloud-ground lightning. 8mm rain fell in short, intense, bursts.
It was very windy on 10 August with several hours in which we had gusts of over 40 knots (one of the criteria for a gale warning) though the average wind speed never approached 34 knots for a true gale. It is not that unusual to have the first of the "autumn storms" coming in from the Atlantic in August.
A feature of our summer every year is "Spanish Plumes": very hot airmasses move northwards from Spain, Portugal or the Mediterreanean area and become unstable (able to form convection clouds because the air above is cooler than the air at the ground and so hot air from the ground will rise to great heights forming towering clouds) as it moves across France and the English Channel.
The first of these arrived on 18 June. We had torrential rain with periods of light rain in between. Although there were warnings of thunderstorms overnight, none occurred here.
It felt brutally hot and humid on 25 July, when records were broken further inland, though sea breezes here kept it to a just bearable 28.8C and a dew point of 21.6C indicating very moist air. We saw a couple of short, intense showers, which hardly cooled things at all.
The final period of summer heat, which gave the hottest day, was around 26th August, where hot continental air sat in a high pressure environment over us and was heated further. The high pressure stopped much cloud or any rain from developing.