The averaging period used for the following assessment was 1961-1990.
Another warm month across all parts of the UK in terms of mean temperature, but minimum temperatures were slightly below average over the SE. Very dry over Southern areas, but parts of N England and N Wales seeing above average rainfall. Very sunny over SE England and East Anglia.
Boscombe Down (Wiltshire) had their coldest September night since 1931, with a temperature of -0.1 on 24th. Redhill (Surrey) recorded a low of -2.8 on the same night.
England and Wales diary of highlights
Mainly dry, sunny and warm, especially in the south. Very warm at times during the first three weeks, then becoming cooler and more unsettled.
1st to 4th High pressure migrated slowly across the UK from the Atlantic to the Low Countries bringing dry weather with good sunny periods and some warm temperatures later.
5th to 11th A rather unsettled period with rain at times as secondary depressions and their associated fronts crossed the region. After a very warm start on the 5th the first band of thundery showers affected many parts on the 6th, with more rain spreading in on the 7th as a low approached southern areas from Biscay. Wet in many places on 8th/9th as more depressions tracked close by. The rain was heavy at times in the north with thunder mixed in. A low near the Thames Estuary on the 10th gave rain in the north and east. More Atlantic fronts brought rain and drizzle to many places on the 11th, while western and northern areas were affected by hill and coastal fog.
12th to 17th An anticyclone which formed over the UK drifted east to the near continent retaining the region under its influence. Dry, sunny and very warm or hot weather prevailed, 28.4 °C being recorded at Gravesend in Kent on the 17th. Patchy mist and fog in the morning cleared quickly.
18th to 22nd A cold front was stalled over north Wales and northern England for much of the period, bringing rain to these parts, often heavy and prolonged. The rest of England and Wales continued to bask in very warm sunny weather, with any mist or fog patches being readily burnt off after dawn. The cold front advanced south during the 22nd providing some heavy and much needed rain to the region. In the south-east, temperature drops of 10 °C in less than an hour were noted in many places.
23rd to 25th High pressure established itself again then drifted east maintaining sunny dry conditions. A number of places had air frost on the 24th, -2.8 °C being recorded at Redhill Airport in Surrey. At Boscombe Down in Wiltshire it was the coldest September night since 1931.
26th to 28th Occasional showers and sunny periods as a weak cold front moved southwards during the 26th.
29th to 30th An unsettled spell, with rain and showers affecting many parts of northern England and north Wales, and 25 mm of rainfall reported at Valley (Anglesey) on the 29th.
Scotland diary of highlights
Dry and warm. Cloudy spells alternating with brighter and showery conditions.
The first five days were dominated by an anticyclone over England with west or south-westerly winds over Scotland. The weather was mostly dry, warm and cloudy with the temperature rising to 24 °C at Charterhall in the Tweed valley on the 5th.
From the 6th to the 11th areas of low pressure extended between Iceland and Europe. There was some rain or showers during this period, with Dumfries receiving 27 mm on the 7th. However, fronts crossed the country on only one day and one night, and much of the time was spent in air of polar origin with plenty of sunshine. Temperatures fell to freezing in Highland glens on three nights.
South-westerly winds returned to Scotland from the 12th to the 17th with an anticyclone over Europe. Once again the weather was mostly dry, cloudy and warm. There was some rain and wind in the north-west, with a gust of 60 m.p.h. at Barra on the 13th. The temperature fell no lower than 16 °C at many places on the 14th and rose to 25 °C at Tain and Kinloss on the 17th.
From the 18th onward there was a long period of changeable weather, with low pressure to the north and south of the British Isles. Most of the time Scotland was in polar air, with light winds, broken cloud and some cold nights. Snow fell on the hills on 22nd and 23rd and the temperature fell to -2 °C at Aboyne on the 24th. A band of rain pushed north-east across the central belt on the 21st with 48 mm at Saughall in Ayrshire. Another band of rain affected the north on the 24th and moved south-east the next day, with 33 mm at Kinbrace.
Northern Ireland diary of highlights
Warm, dry but dull.
Overall mean temperatures were above average, daytime maximum temperatures consistently around or above normal during the first three weeks of the month. It was a dry month, with most of rainfall being recorded from heavy outbreaks of rain and/or showers on five or six separate occasions.
1st to 4th The weather across the province at the start of Autumn was warm with some sunny spells. It was predominantly dry, though some scattered, light showers occurred on the 1st and 2nd.
5th to 12th Atlantic depressions and their associated weather fronts brought bands of rain and showers. Some heavy downpours occurred locally on the 7th and 9th. Some long sunny spells were recorded during this time; indeed some areas recorded over ten hours of bright sunshine alone on the 8th.
13th to 17th High pressure dominated much of the weather during this period to give dry, warm and settled conditions. Both day and night time temperatures were 2-6 °C above the monthly average over this time. One of the highest temperatures of the month was 23.9 °C, which was recorded on the 13th in northern and western areas of the province.
18th to 21st Rather unsettled conditions prevailed oughout this period. Heavy falls of rain and showers were recorded on the 19th and 21st, with some areas measuring over 25 mm on the 21st alone. Although temperatures were around or slightly above normal they were cooler by around 4 or 5 °C in comparison with the previous week. It was dull over this time, except on the 20th, which was quite sunny, with some areas recording over seven hours of sunshine.
22nd to 28th Although cool, with outbreaks of some rain and showers, this was also quite a sunny period everywhere, though few sunshine amounts were recorded anywhere on the 25th.
29th to 30th September ended with dull, cool conditions along with rain and showers occurring in all areas.