As the weather in the UK turns increasingly Autumnal, it may already seem a distant memory that the start of September saw an unprecedented heatwave in the UK.

For the first time there was a run of seven consecutive days recording 30°C or higher in September. This surpassed the previous longest runs of five days in September 1929 and 1911.

For the 7th consecutive day running, temperatures have surpassed 30°C in the UK, making this #heatwave the longest on record for September pic.twitter.com/h443Pc97k1

— Met Office (@metoffice) September 10, 2023

It was also a notable spell for overnight temperatures, with the first consecutive tropical nights recorded in September.

A significant number of long running weather stations broke their September maximum temperature records, some by quite a margin.

A summary of the notable weather event has now been published, with all the statistics and records outlined and contextualised against the historical record.

Month so far

The notable heatwave has led to some interesting mid-month statistics for the UK, though these are likely to change as the UK moves into a more typical Autumnal spell of weather.

The mean September temperature for the UK is notably above average so far this month, as shown in the graph below. Temperatures are forecast to fall back to normal for the time of year and we are only halfway through the transitional month of September so there could still be a lot of change by the end of the month.

As the heatwave broke there have been a succession of thunderstorms crossing the UK. The map below shows the density of lightning strikes and highlights the areas which have seen the most active thunderstorms through the month so far.

The graph below shows how the heavy rain from these thunderstorms, particularly on 17 September, has put the UK much closer to average for rainfall at this point in the month after what was a very dry start to September.