The Weather Review

Weather Update

August marked the transition to autumn, moving from warm and still conditions to being more unsettled as we entered September.

Temperatures were well above the seasonal norms across the UK, particularly in the first half of the month. High pressure over the continent kept skies clear and air still, allowing high solar generation. This presented risks for power and prices, with Scandinavian regions losing a lot of hydropower reserves in the heatwave, and French nuclear facilities having to limit generation due to cooling waters becoming too warm. The dry and static weather lead to thunderstorms in some parts of the UK.

The second half of the month was much cloudier with low solar radiation. A high incidence of large storms forming across the Atlantic caused spikes in rainfall. Fortunately, there were limited flooding issues in the UK, while more recently the USA has been hit by multiple tropical storms. The intense period of hot weather allows large low-pressure systems to form in the Atlantic and create cyclones – and we sometimes experience the aftermath of these in the UK. Even though cloudy skies reduced temperatures and brought windier days towards the end of August, the average temperature for the month was still above average, due to air masses moving in from the Mediterranean.

Looking to September, early estimations suggest somewhat of a replica of August. The first half of the month has been forecast to have settled conditions, with wind levels staying low. Dry and relatively warm weather is expected for the southern UK, with overnight mist common. This is caused by clear skies allowing the sun to heat surface air, with high pressure stopping it from rising. In the evening there are few clouds to trap the heat overnight, so the air condenses at ground level.

The second half should be blustery, with the Atlantic again expected to bring in low pressure from the west. High winds should mean a lot of wind generation late in the month.