The averaging period used for the following assessment was 1981-2010.
UK climate video
At the start of September, north-westerly winds brought cool and showery weather to the UK. After this, the weather was dominated by high pressure from the 5th until the 11th and again from the 25th onwards, which mostly brought dry weather with plenty of sunshine, especially near the end of the month. However, the weather was rather changeable from the 12th to the 24th, and despite the two fine spells, it was a generally cool month. The fine spell during the last few days brought warm days but also some notably cool nights.
The UK mean temperature was 11.9 °C, which is 0.8 °C below the 1981-2010 long-term average. It was coldest relative to average across East Anglia and south-east England, but parts of north and north-west Scotland were slightly warmer than average. It was a very dry month in western Scotland and north-west England, with less than a third of the normal rainfall in many locations, but rainfall was near or slightly above average in parts of south-east England. September was a sunny month over most of the UK, especially so in western Scotland, but sunshine totals were below average for Orkney and Shetland.
The UK monthly extremes were as follows: A maximum temperature of 24.0 °C was recorded at Braemar (Aberdeenshire) on the 30th, and a minimum temperature of -1.3 °C was recorded at Braemar (Aberdeenshire), also on the 30th. This would appear to be the only occurrence in historical records where the monthly temperature extremes have occurred at the same station and on the same day; the diurnal temperature range of 25.3 °C is also among the largest on record for the UK. In the 24 hours ending at 0900 GMT on the 15th, 86.2 mm of rain fell at Pembroke Dock, Pembrokeshire. A wind gust of 78 mph was recorded at Needles Old Battery (Isle of Wight) on the 15th.
The image below shows the view north from Goatfell (874 masl) looking north-west toward Cir Mhor (799 masl) on the Isle of Arran around mid-day on 7 September. High pressure was dominating the UK's weather, with the top of the peaks of Arran projecting above the low-level cloud trapped below. Courtesy Mike Kendon, Met Office.
This satellite image on 7 September of the northern half of the UK shows clear skies across much of Scotland but low-level cloud affecting western coasts. Copyright Met Office / NOAA.
The image below shows the supermoon lunar eclipse at 0200 GMT 28 September. Courtesy Peter Sykes, Met Office
This was a relatively quiet month with few weather impacts.
On the 2nd very heavy showers caused localised surface water flooding and impacts on transport for a time across parts of North Wales and the Wirral. There were also reports of over 100 homes being evacuated in Moreton (Wirral) after the River Birket "overtopped" following heavy rain.
There were several instances of localised flooding in mid-September in southern and eastern England. On the 15th, localised surface water flooding was reported in areas such as Dorset, East Sussex, Lincolnshire and Teesside. On the 16th, there were further reports of localised flooding causing travel disruption in East Anglia, Surrey, Dorset and Hampshire, with two separate reports of drivers being rescued from cars trapped in flood water. On the 18th, heavy downpours were reported to have affected road and rail travel in parts of Suffolk, Norfolk and Essex.
Toward the end of the month, high pressure brought some overnight frost and lingering fog; this fog being the main weather hazard across parts of the UK toward the end of the month.
Much of the country enjoyed clear skies for the supermoon lunar eclipse overnight 27 to 28 September.
England diary of highlights
September began with a cool, showery north-westerly type, but high pressure then brought a spell of mostly dry and sunny weather. It was generally cool and unsettled from the 12th to the 24th with some heavy rain around mid-month, but the month ended dry and sunny with warm days and cool nights.
The mean temperature for September was 1.1 °C below the long-term average, making it the coolest September since 1994. Rainfall was 73% of average, but East Anglia and south-east England had slightly above average rainfall, while Cumbria and north Lancashire had less than half the normal amount. Sunshine was 127% of average and it was particularly sunny in the west, but sunshine totals were slightly below average in parts of Yorkshire.
1st to 5th:
The 1st was a day of sunshine and widespread showers, some of the showers being heavy and locally thundery with Crosby (Merseyside) recording 32 mm. It was a similar story on the 2nd with only the south-west escaping some widespread and heavy showers. The 3rd was cooler in a north-westerly breeze, and mostly cloudy in the east, although the showers were generally lighter and less widespread. The 4th was mainly cloudy in the north and west with the east seeing the best of any sunshine although isolated showers broke out in the far north and south later in the day. The 5th remained mainly dry but generally cloudy with very isolated showers along the east coast.
6th to 11th:
High pressure became established over the country, giving mainly dry and sunny days from the 6th to the 10th although mist and low cloud affected eastern areas at times. The 11th was dry and bright for much of the day but it became cloudier and windier from the west during the afternoon and rain edged into western areas during the evening.
12th to 19th:
There was rain in the north and east early on the 12th but this cleared to give a bright day with only a few isolated showers. The 13th was mainly dry and sunny, but rain affected the far south-east and south-west during the afternoon. A very unsettled day followed on the 14th, with widespread heavy showers and thunder in parts of Lincolnshire and Humberside where over 30 mm of rain was recorded. An area of persistent heavy rain was slow to clear north-eastern areas on the 15th with Loftus (Cleveland) recording 48 mm, while most other areas saw scattered showers and sunny intervals. After a bright start on the 16th, rain spread into southern areas during the afternoon and spread slowly north-east with High Beach (Essex) recording 30 mm. The 17th saw scattered showers in northern and western areas while the east was mainly dry with sunny spells. The 18th was a day of sunshine and scattered showers, the heaviest showers being in the south-east with isolated thunderstorms. The 19th was dry and sunny under a ridge of high pressure.
20th to 24th:
After a dry and bright start on the 20th, cloud increased during the afternoon with rain spreading into western areas during the evening. It was generally overcast and wet for much of the country on the 21st with rain edging slowly eastwards during the day, brightening up in the west later. The 22nd was a day of sunshine and scattered showers, with the heaviest and most frequent showers in the south. It began dry on the 23rd; although most parts remained dry, patchy rain affected some western areas during the afternoon. Another showery day on the 24th although these were quite scattered and central areas stayed mostly dry.
25th to 30th:
High pressure built from the south during the 25th resulting in a mainly dry day with sunny spells. The 26th until the 30th were mainly dry and sunny across the whole country, although there was fog and mist in many central areas during the mornings, and it was chilly, with a minimum of -0.5 °C at South Newington (Oxfordshire) on the morning of the 27th.
Wales diary of highlights
September started unsettled with north-westerly winds and some rain or showers. There were settled spells between the 6th and 10th, and again from the 25th to the end of the month, but a more unsettled period in between. Despite spells of fine, settled weather with high pressure established, it was a generally cool month.
The mean temperature was 1.1 °C below the long-term average, the coolest September since 1994. Wales had 62% of average rainfall overall, and 136% of average sunshine. It was the equal-third sunniest September in a series from 1929.
1st to 4th:
It was cool and showery on the 1st, and the showers were particularly frequent and heavy in the north, persisting for most of the day. It was similar on the 2nd, with frequent and heavy showers concentrated in the north. The 3rd was cool and cloudy with widespread but mainly light showers. It was mostly dry but cool and cloudy on the 4th with isolated showers later in the day.
5th to 11th:
After a cloudy start to the 5th it became bright and sunny later. It was dry with sunny spells for most of the country on the 6th, but cloudier in the north. It was mostly dry on the 7th with good sunny spells, albeit cloudy across Anglesey. A foggy start for some on the 8th, clearing to give widespread sunny spells. A dry, warm day followed on the 9th and it was similar again on the 10th, following early fog patches, with further sunny spells especially across the south and west coasts. There was more of the same on the 11th albeit a little cooler, and it was also cloudier over the Bristol Channel and Pembrokeshire coasts.
12th to 17th:
There was a mix of sunshine and showers on the 12th, but the showers cleared by late afternoon. After a wet start for north-western parts on the 13th, rain cleared by late morning but further rain and showers moved into the south later. A very wet day everywhere on the 14th, particularly in the south with 30 mm falling widely and 53.6 mm recorded at Milford Haven (Pembrokeshire). Sunshine and showers again on the 15th and surprisingly windy - 47 mph recorded at St.Athan (South Glamorgan) - although there were not many showers in the north. Low pressure was never far away on the 16th but it remained dry throughout the day. There was a bright start on the 17th but showers developed later, particularly in the south, and persisted overnight.
18th to 24th:
Early rain gave way to a mainly dry day on the 18th, although there were isolated showers. It was more settled on the 19th with widespread warm, dry and sunny conditions. It was cloudy with patchy fog to start on the 20th, and rain spread from the west by evening. There was more rain early on the 21st, clearing from the west during the morning to leave a mostly dry bright afternoon, before organised showers produced locally heavy falls during the evening. There were more showers on the 22nd, these particularly prolonged and heavy over Snowdonia. It was dry and bright initially on the 23rd before cloud and patchy light rain moved eastwards from late afternoon. There was a mix of sunshine and showers for the 24th, the showers heavy and frequent in the south during late morning.
25th to 30th:
It was dry throughout on the 25th with some sunshine, as high pressure built from the south. It was dry again on the 26th, but cooler and cloudy. There was patchy mist and fog on the 27th, then warm, sunny, dry conditions prevailing through to the end of the month with some slight overnight frost in the valleys.
Scotland diary of highlights
The month began cool and showery, but high pressure then brought mostly dry sunny weather until the 11th. It was unsettled and cool at times between the 12th and 25th, but dry sunny weather returned near the end of the month.
The mean temperature for September was 0.1 °C below the long-term average. It was slightly warmer than average in the north but cooler than average in the south. It was a dry month with only 37% of the long-term average rainfall; this was the equal-fourth driest September in a series since 1910, though not as dry as September 2014. Scotland as a whole had 124% of average sunshine, and sunshine totals were more than 50% above average in parts of the north-west and around Glasgow, but generally close to average near the east coast.
1st to 5th:
It was cool and showery on the 1st; the showers were frequent in the east but it was drier and brighter in south-western parts. Showers were lighter in nature on the 2nd and it was again drier in the south-west. There was persistent rain over the Borders on the 3rd, while elsewhere it was mostly cloudy with scattered showers. There was a dry start to the 4th but patchy light rain moved south from late morning with scattered showers following behind. Showers continued over Grampian until mid-afternoon on the 5th, but it was otherwise dry and bright with prolonged sunny spells especially in southern parts.
6th to 11th:
It was mostly dry and sunny on the 6th but remained cloudy in the north-west with occasional patchy, light rain. It was again rather cloudy in north-western parts on the 7th but fog in the south soon cleared to leave a dry and sunny day for most. There was early cloud and fog again on the 8th with sunny spells developing across western and central parts. The 9th was mainly dry and cloudy, but early fog and mist cleared across the Grampians and north-west Highlands around midday to leave a sunny afternoon and evening with temperatures reaching 21.4 °C at both Achnagart and Kinlochewe (Highland). It was dry, sunny and warm for most on the 10th but cloudier with some drizzle in the east; similarly fine on the 11th but cooler over the country as a whole.
12th to 20th:
The 12th was cool and wet for all parts with rain, often heavy, moving north-eastwards. Rain over the Western Isles on the 13th cleared late morning, and it was otherwise cloudy with showers, locally heavy, but the Northern Isles remained dry and bright. Cloudy again on the 14th with the heaviest rain over the Northern Isles, although southern Scotland was more showery, and it was dry and sunny over the Western Isles. Central and southern parts stayed dry with variable amounts of sunshine on the 15th but there was rain later for northern parts. There was a mix of sunshine and showers on the 16th but it was cloudier and wetter in the north. A northerly wind brought widespread showers on the 17th, particularly to the West Highlands. It was mostly dry and bright but cooler on the 18th, and particularly sunny in the west. It was dry throughout the country with widespread sunshine on the 19th - temperatures reaching 18.2 °C at Braemar (Aberdeenshire).
21st to 25th:
The weather changed abruptly on the 20th with heavy rain for the south, and lighter, more showery outbreaks elsewhere. It was dry for most areas on the 21st but later rain over the south-west moved slowly north-eastwards with totals in excess of 25 mm over Grampian. More cloud and rain for Grampian and the north-west Highlands on the 22nd, fizzling out southwards, while remaining drier and sunnier further south and west. It was wet again on the 23rd as a rain band pushed east with showers behind. It was dry and bright to the east of the Grampians to start the 24th, but showers, often heavy, for western parts, spread to all regions later. It was showery again on the 25th but the showers became confined to north-eastern areas.
26th to 30th:
Much more settled, drier conditions prevailed from the 26th onwards, although isolated light showers persisted in the north on the 26th. After an overnight frost in the glens, the 27th was fine. Dry, sunny and warm conditions continued through to the end of the month. It was particularly warm on the 29th with temperatures reaching the low twenties Celsius in the east and there was more of the same on the 30th with the temperature at Braemar rising from a minimum of -1.3 °C to a maximum of 24 °C.
Northern Ireland diary of highlights
September began cool and showery with northerly winds. There were settled spells from the 5th to the 10th and from the 25th onwards, and the end of the month was very sunny, but there were often fairly changeable and cool conditions in between.
Despite the fine spells, the mean temperature was 0.6°C below the long-term average. This was a dry month, with only 51% of average rainfall, though not as dry as September 2014. Sunshine was 115% of average, making it the sunniest September since 1997.
1st to 4th:
There was a cool and showery start on the 1st, but the showers decayed by early evening. Sunshine and showers again on the 2nd, and the showers were mainly light but continued for most of the day. It was cool and cloudy with more showers on the 3rd, but the showers cleared away by early afternoon. It was a mainly cloudy day again on the 4th, and some patchy light rain spread from the north by evening.
5th to 10th:
It was mostly dry and sunny, if rather cool, on the 5th with isolated light showers, but it was mainly cloudy on the 6th with further light, isolated showers. Cloudy again on the 7th with a few pockets of light rain or drizzle. A mainly dry and cloudy day followed for the 8th, but the cloud melted away leaving late evening sunshine. It remained cloudy and misty but dry on the 9th, but the cloud cleared later. It was dry and sunny on the 10th.
11th to 14th:
It started dry and bright on the 11th but rain, heavy at times, spread from the west by mid-afternoon. It started dull and wet on the 12th with rain, frequently heavy, for all regions, but this cleared from the south-west followed by sunshine and scattered showers. After a dry, sunny start on the 13th, cloud and rain soon spread from the south. It was dry and quite sunny for northern areas on the 14th but rain moved into the south, albeit mainly light and showery in nature.
15th to 19th:
There was a cool north-westerly on the 15th but remaining dry and feeling warm in widespread sunshine.
After a chilly night, with -1.0 °C recorded at Katesbridge (County Down), the 16th was again dry and sunny. It was cloudier and cooler on the 17th with widespread showers throughout the afternoon and evening. It was warm and dry on the 18th with widespread sunshine. Dry again on the 19th but cooler and cloudier.
20th to 25th:
The weather was cloudy and wet on the 20th, and again on the 21st although the rain was more showery in nature and cleared by early evening. The 22nd was a day of sunshine and showers, the showers locally heavy in the morning but fading out after midday. It was a cloudy, breezy day on the 23rd with mainly light and patchy rain during the day, clearing away by the evening with occasional heavy showers behind. Showers continued throughout the 24th, and were particularly heavy over north-western parts. There were early light showers on the 25th, clearing by mid afternoon.
26th to 30th:
High pressure dominated towards the end of the month with widespread dry, sunny conditions prevailing. A cooler night on the 27th led to early mist and fog patches, and temperatures reached the high teens on the 28th, particularly in the north-west. Warm, dry, sunny conditions continued on the 29th and 30th.