UK weather: This heatwave is very unusual – here’s why
It’s very rare for the UK to see three consecutive days where temperatures are above 30C (86F) in September.
According to Met Office data, it’s happened just four times before this year: 1898, 1906, 1911 and 2016.
Now, 2023 has joined the list – and smashed records for the the longest September hot spell ever.
On Thursday at 1pm, the temperature in Northolt was 30.2C (86F), which makes it the fourth day in a row where the 30C mark was breached.
And forecasters predict that we could see five or six consecutive days above this level before the week is out.
There are other records that are unlikely to be broken this week.
The record for the UK’s hottest day in a September was set all the way back in 1906, when 35.6C (96F) was seen in South Yorkshire.
While such a long heatwave so late in the year is unusual, it is no surprise to meteorologists.
The UK’s climate is changing
Although we don’t have a full month of this year’s data to compare with, the average daily temperature in September was 13.2C (55F) in the 10 years to 2022. That’s an increase of almost 1.5C since the mid-1990s.
Thursday’s forecast of 32C is 12C hotter than the average high for this time of year.
The Met Office told Sky News: “It’s evident in our observational records that the UK climate is already changing.
“What we’re seeing, and what we expect to continue seeing, is an increase in the intensity, duration and extent of heatwaves in the UK.
“While the UK climate has always experienced natural variability of warm and cool weather, what climate change does to heat events is add that extra layer of background global temperature rises to the meteorological conditions, helping to pep temperatures up.”
Met Office records – dating back to 1884 – show a clear increase in September average temperatures, and this rise is expected to carry on over the years.
By 2070, meteorologists project that 30C on two or more days will become more likely – with southern parts of the UK experiencing this 16 times more frequently than today.
US-based researchers Climate Central have calculated that the late heatwave was made five times more likely because of climate change.
Tropical storms have also helped push a high pressure system over the UK and central Europe – while further south, Greece and Spain have been hit with torrential downpours and flooding after a summer of intense wildfires.
The Greek islands, south of France, Ibiza and LA will all be cooler than London this weekend.
The UK Health Security Agency has issued an amber warning for heat lasting until Sunday at 9pm – meaning extra stress will be placed on the health service because of the weather.
Those over 65 or with respiratory and cardiovascular diseases are at greater risk.
Consecutive days of heat can lead to more health issues than one-offs as prolonged heat puts more of a strain on our bodies with little respite, especially at night.