Spring was cool: after a reasonable March, both April and May were cold, although April was also dry and sunny, but May very wet and dull - April was the fourth driest on record and May the fourth wettest.
January. A cool month, but there was a big north-south divide, with the south being mild and Scotland very cold. Unusually there was more sunshine in January in Scotland than in England, making it the fourth sunniest January there since records began (in 1919), while the SE of England only saw 35 hours of sun on average all month. NW Scotland was dry and the Highlands very dry, but it was a very wet month in the south. The month started very cold with snow and some harsh forsts: it was -12.3C at Loch Glascarnoch on the 6th, and -13.0 at Dawyck (Peeblesshire) on the 9th. It then turned milder in the south, but stayed largely colder in the north, with the country becoming something of a battleground between cold and mild air masses. Named Storm Christopn brought windy and very wet weahter to the UK on the 19th - 21st, with 100 mm of rain widespread, leading to flooding, and bringing cold air and snow to the Midlands. On the recording day ending on the 20th 132.8 mm fell at Honister Pass in Cumbria. It then became milder in the south but remained cold in Scotland. It reached +14.2C at Pershore (Worcester) on the 28th, but with a minimum of -13.0C at Braemar on the 31st.
February. Cold first half, very mild second half, making for a near average month overall, which hides a very cold, snowy spell, particularly in the east, midmonth. A wet month, with 116% of average rainfall, and near average sunshine overall. The highest temperature of the month was 18.4C at Santon Downham (Suffolk) on the 24th, and a minimum of -23.0C at Braemar on the 11th. A snow depth of 38 cm was recorded at Aboyne (Aberdeenshire) on the 10th. 125.8 mm of rain fell at Honister Pass (Cumbrai) on the 23-24th. The far north of Scotland was particularly sunny and dry, with Shetland being 54% sunnier than average.
March. Unsettled; overall slightly warmer than average, with a cold start but mild second half to the month. A plume of hot air from the south gave 24.5C in Kew on 30 March, and generally there widespread warm temperatures across the south at the end of the month: this particular reading was the highest for March since the record-breaking 1968. It was quite a dry month, with 89% of rain overall, being drier in the south and east and wetter in the north and west. Sunshine quantities overall were average. The lowest temperature of the month was -8.5C at Braemar on the 6th. 177.2 mm of rain fell at Seathwaite (Cumbria) on the rain day ending on the 29th. It was very windy in the south on the 13th, with some snow in the Highlands on the same date.
April. Very cold, dry, and sunny, mostly anticyclonic wth frequent north winds. There were an unusually large number of night-time frosts, with the mean minima well beneath average. Nationally, on average April was cooler than March - the last time this happened was 2012. It was the fourth driest since systematic records began in 1862. The southeast coast weas particularly dry: Shoreham recorded less than 1 mm for the month. There was 152% of expected sunshine, hence just surpassing 2020; it was particularly sunny in northern England and southern Scotland. The highest temperature of the month was 21.4C at Treknow (Cornwall) on the 1st, and the lowest -9.4C at Tulloch Bridge on the 12th.
May. May began very cold, and was generally cold, windy, wet, dull, and unsettled, except for the final few days, Nationally it was the coldest May since 1996. The maxima were particularly low. Many places saw double the average rainfall, with an average of 171%, making this May the fourth wettest since 1862; Wales had its wettest May on record (with 245 mm), as did Devon. Sunshine was in short supply (apart from Northern Ireland), with 86% of the long-term average. The only warmth came right at the end of the month, when 25.1C was recorded at Kinlochewe (Ross & Cromarty) on the 31st. The lowest minimum of the month was -61C at St. Harmon (Powys) on the 2nd. The highest 9-9 raifall total was 103 mm at Mickleden (Cumbria) on the 20th-21st. Snow lay to 1 cm at Achiltibuie (Ross & Cromarty) on the 5th. All in all a May to forget.
June. After a miserable May, June 2021 in contrast began warm, dry and sunny, with 28.3C recorded at Northolt (north London) on the 2nd, before it turned somewhat cooler. It reached 29.7C at Teddington (London) on the 14th. The second half was cooler and unsetteld, with some heavy thunderstorms in the southeast. Overall it was nationally slightly warmer than average. It was dry in the north, with a third of the rainfall in parts, but very wet in the southeast, with double the average rainfall, giving an overall UK average of 59%. Overall there was 107% of sunshine, although it was more cloudy in parts of the west. The lowest temperature of the month was -2.4C at Altnaharra on the 22nd. 74.0 mm of rain fell at Princetown in Devon on the rain day ending on the 28th. Meanwhile, in an extraordinary heatwave in the NW of America, 49.6C was reported in the town of Lytton, British Columbia, not far from Vancoubrt in Canada; the town was destroyed in a forest fire the next day.
,July. July 2021 was very warm, with a long warm spell in the middle sandwiched between an unsettled beginning and end. It was a fine month in wetern Scotland. There was some exceptionally heavy rain in Edinburgh on the 4th, with 41 mm of rain recorded in one hour at the Botannical Gardens, leading to flooding. The Azores High then built, giving settled and increasingly warmer weather, as well as cloudless skies, across most of the UK. At the same time a low led to exceptionally serious and tragic flooding in Germany and parts of surrounding countries. There was a heatwave midmonth, particularly affecting the south and west, with 8 consecutive days recording above 30C. A new record highest temperature of 31.2 C was first set on the 17th in Northern Ireland at Newtownards in County Down, beating 1976 and 1983. It was then 31.6 at Heathrow on the 18th, 31.4 there on the 19th, and 32.2 there on the 20th. The heat then moved west. The Northern Ireland record was broken yet again on the 21st with 31.3 C at Castlederg; it was 31.1 at North Wyke (Devon). It was then 31.4C at Armagh Observatory on the 22nd (31.2 at Gogerddan, Ceredigion), and then 30.1C at Castlederg on the 24th (29.0 ºC at Castle Douglas in Scotland). 29.3 ºC was reported at Threave Garden (Kirkcudbrightshire) on the 22nd. In the heat there were some exceptional thunderstroms with large hail in the SE and East Midlands, particularly on Tuesday 21st; 44 mm of rain fell in a thunderstorm at Marham (Norfolk). Overall it was the fifth warmest July on record. Rainfall was very variable, with overall 93% of the average, but parts of England and the Highlands were very wet, while Northern Ireland and western and northern Scotland were very dry. Sunshine was 111%, particularly in the west and western Scotland; Lochaber had 70% more sunshine than average. It was third hottest July in Scotland on record. The month ended with gales in southern England on the 30th. It was very hot in Europe, with a minimum over 36 ºC in Greece on the 31st, while maxima were about 44C. Wildfires were widespread. July 2021 was the hottest month on Earth since at least the beginning of the twentieth century.
August. An unsettled first half, but more anticyclonic from the 23rd. Close to the centre of the high pressure system, there was a late heatwave in Scotland: 27.2 ºC was recorded at Tyndrum in the Highlands on the 25th. On the whole it was a month of average temperatures, although relatively cool in the southeast, slightly drier than average overall, and dull, athough there were wide geographical variations: it was wettest in the southeast, and very dull in the Midlands and parts of eastern England (the dullest on record for 60 years in parts) while sunny in western Scotland. Across the world: Europe recorded its hottest ever day, with 48.8 ºC at Syracuse on Sicily on Wednesday 11 August, as "Anticycone Lucifer" enabled great heat to build.
September. The month saw a notable early heatwave. 1999 saw the first September day over 30 ºC since 1973; since then it has been fairly frequent, but 2021's heatwave saw two consecutive days over 30 ºC, 7th and 8th (Northolt 30.3 on the 8th, Gogerddan near Aberystwyth 30.7 on the 7th). There was a thundery breakdown on the 9th, but it remained warm. The heat was widespread across Britain, with Scotland recording its hottest September day since 1906 with 28.6 ºC at Cherthall in the Borders, on the 8th. Wales recorded a tropical night, with a new record high minimum for Wales on the 7th of 20.5 at Aberporth on Cardigan Bay.