September marks the beginning of meteorological autumn, but the UK’s weather during the month can retain the warmth of summer or offer an early indication of colder conditions to come.
Historical observations show an exceptional range of September weather. UK records extend from temperatures above 35°C to overnight lows well below freezing, alongside episodes of intense rainfall, powerful winds and prolonged sunshine.
In this blog, we’ll look at September’s weather extremes, from exceptional heat and sunshine hours to strong winds and heavy rain.
Exceptional September heat
The UK’s highest September temperature is 35.6°C, recorded at Bawtry in South Yorkshire on 2 September 1906. This is also England’s record for the month.
That same hot spell produced national records elsewhere. Gordon Castle in Moray reached 32.2°C on 1 September 1906, setting Scotland’s September record, while Hawarden Bridge in Clwyd recorded 32.3°C on the same day, setting the record for Wales.
Northern Ireland’s highest September temperature is much more recent. Castlederg in County Tyrone reached 28°C on 8 September 2023.
Warmth can also persist throughout the night. London’s St James’s Park recorded a daily minimum temperature of 21.7°C on 5 September 1949, the highest September daily minimum for both the UK and England.
Wales has recorded a minimum of 20.5°C at Aberporth in Dyfed on 8 September 2021. Scotland’s record is 18.7°C at Achnagart in Ross and Cromarty on 29 September 2011, while Northern Ireland reached 18.3°C at Armagh in 1898 and Belfast Ravenhill in 1999.
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An early taste of colder weather
At the opposite end of the scale, September can bring conditions more reminiscent of late autumn.
The UK’s lowest September daily maximum is just 4.4°C, recorded at Braemar in Aberdeenshire, Scotland, on 29 September 1915. England’s lowest maximum is 6.2°C at Malham Tarn in North Yorkshire on 27 September 1974.
On the same date in 1974, temperatures reached only 6.5°C at Alwen in Conwy and Lake Vyrnwy in Powys. Northern Ireland’s lowest September maximum is 6.8°C at Divis Mountain in County Antrim on 27 September 1975.
Overnight temperatures have fallen considerably lower. Dalwhinnie in Inverness-shire recorded -6.7°C on 26 September 1942, the UK and Scottish record. England’s record is -5.6°C, observed at Santon Downham in Norfolk and Grendon Underwood in Buckinghamshire on 30 September 1969.
The September minima for Wales and Northern Ireland are -5.5°C at St Harmon in Powys on 19 September 1986 and -3.6°C at Katesbridge in County Down on 29 September 2018 respectively.
You can explore these records using our interactive graphic below.
Heavy rain and strong winds
September’s extremes are not confined to temperature. West Stourmouth in Kent recorded 190.7mm of rain on 20 September 1973, the highest September daily total for the UK and England.
The equivalent records are 157.7mm at Skye Broadford in Inverness-shire on 13 September 2005, 171.0mm at Clwyd in Gwynedd on 2 September 1983 and 147.2mm at Dungonnell in County Antrim on 24 September 2012.
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The UK’s strongest September gust was 112mph, at Dounreay in Caithness on 28 September 1969. England’s record is 97mph, at High Bradfield in South Yorkshire on 27 September 1975. Wales reached 84mph in Valley, Gwynedd on 5 September, 1967, and again on 27 September, 2023, in Capel Curig, while Northern Ireland recorded 91mph, at Killowen in 2018.
Sunshine extremes
The sunniest September day delivered 13.6 hours of sunshine at Fyvie Castle in Aberdeenshire on 1 September 1964. England recorded 13.4 hours at Poole and Weymouth in 2002, while on the same day, Wales reached 13.3 hours at Tenby. Northern Ireland’s record is 12.9 hours at Lowtown in 1965.
Despite September’s colder records, no lying snow depth appears in our records.
Together, these records show September’s place as a month of transition. Summer heat can linger, but increasingly long nights offer greater opportunities for frost, while Atlantic low-pressure systems can bring heavy rain and damaging winds.
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