August 2004

The averaging period used for the following assessment was 1961-1990.

UK overview

A very wet month, with many areas receiving double their average August rainfall. Sunshine totals were close to average in most parts, although parts of south-east Scotland and north-east England had considerably lower than average amounts. Shetland's sunshine total was much higher than average. Mean temperatures were generally one or two degrees Celsius above average.

On 16 August, there was devastation in Boscastle (north Cornwall) due to severe flooding, and at nearby Otterham 200.4 mm of rain fell in 24 hours. Lesnewth near Boscastle had 64.8 mm of rain in an hour. Eskdalemuir recorded over 300 mm during the month.

England and Wales diary of highlights

Very warm or hot for the first week with thundery showers. Unsettled for much of the month with some torrential rain. Fine in many places on the last two days.

1st to 8th: Generally sunny on the 1st except in eastern coastal parts, where low cloud and mist was persistent. Over the following week, the weather became more unsettled with showers becoming widespread and thundery. On 3rd, 42.4 mm of rain was recorded at High Wycombe in an hour. It was very warm or hot and on the 7th and 8th, 31.5 °C was recorded in central London and at Northolt, while eastern coasts again had misty low cloud.

9th to 15th: The hot weather culminated in some warm, sultry night nights and at Marham, Norfolk, a minimum of 21.9 °C was recorded on the morning of the 9th, the warmest night there since at least 1957. Slow moving fronts and troughs gave an unsettled period, with prolonged heavy thundery rain or heavy thundery showers. Wittering recorded 90.8 mm in the 24 hours to 0900 on the 10th, Kirklees 80.6 mm, with 64.0 mm falling in 12 hours, and Pembrey Sands (Carmarthenshire) had 44.2 mm of rain in the three hours ending 0200 on the 12th. The 14th was fine in most places but this was only a temporary respite as Atlantic fronts edging into south-western parts on the 15th heralded another unsettled period.

16th to 17th: Rain pushed north-east overnight into the 16th followed by some torrential thundery downpours. On the 16th there was devastation in Boscastle (north Cornwall) due to severe flooding and at nearby Otterham 200.4 mm of rain fell in 24 hours. Lesnewth near Boscastle had 64.8 mm of rain in an hour. On the 17th the far west of Cornwall had heavy rain with 58 mm in three hours at Camborne, 64.4 mm in the 12 hours to 2100, and 31.6 mm in an hour at Culdrose, 56.2 mm to 2100.

18th to 29th: Low pressure dominated with temperatures generally close to average. Northern England had heavy rain overnight into the 20th. There were further thundery showers and at Bedford 41.8 mm of rain was reported in the hour to 1700, with a 12-hour total of 55.2 mm to 2100. North-west England bore the brunt of the heavy rain on 25th with 41.6 mm of rain recorded at Manchester Hulme. There were a few drier days notably the 25th and 28th while fronts cleared south-east during the 27th. West to north-west winds following in the wake of a low on the 28th brought a chilly feel.

30th to 31st: The 30th was rather cool in many places with fresh winds and there were some showers in the east. A ridge of high pressure on the 31st brought a fine day to most places to close the month.

Scotland diary of highlights

Very wet in east and south.

Cyclonic spells in the middle of August generated some unusually heavy rain, especially in areas exposed to the south-east. This culminated in a landslide in Glen Ogle on the 18th, and Leuchars experienced its wettest month since records began in 1922. There was also some very warm air in the first half of the month and Aviemore recorded its warmest night on record on the 9th. While much of southern and eastern Scotland suffered from the mid-month deluges, Shetland enjoyed well above average sunshine.

An anticyclone in the Norwegian Sea with a light south-south-easterly airflow over Scotland gave a fine start to the month away from the east coast. The temperature reached 27 °C at Aultbea on the 2nd.

From the 3rd to the 6th a slack pressure field covered Scotland and weak fronts gave unsettled weather with a good deal of cloud and some outbreaks of rain. Eskdalemuir recorded 65 mm on the 3rd. However, it remained warm with the temperature rising to 26 °C at Charterhall on the 6th.

Fair weather returned on the 7th and 8th with a south-easterly wind and the temperature rising to 28 °C at Broadford and Aultbea.

On the 9th, fronts associated with a deep depression to the south-west of Ireland reached the south-west of Scotland and became slow moving. Much rain fell over the southern half of Scotland during the next four days with 48 mm at Oban overnight on the 8th/9th, 51 mm at Strathallan on the 9th and 56 mm at Bishopton on the 10th. Fair weather persisted in the north with a minimum temperature of 20 °C on the 9th and a maximum of 27 °C at Aultbea the next day.

The depression eventually cleared away to the east on the 13th and a ridge of high pressure developed to give fine weather for a couple of days.

Low pressure in the Atlantic extended its influence over Scotland on the 15th and unsettled weather with much cloud and some outbreaks of rain returned. A deep depression developed and moved north-east across the north of England on the 18th, pushing an active front and its associated band of rain north across Scotland. The rain was heaviest in places exposed to the east and 50 mm was recorded at Loch Tay, close to the site of a landslide in Glen Ogle. There was even more rain (64 mm) in a storm at Lerwick.

The depression was followed by cool northerly winds on the 20th and a broad ridge of high pressure on the 21st and 22nd. This gave plenty of sunny weather with the temperature at Tulloch Bridge falling to -1 °C.

Unsettled and changeable conditions returned between the 23rd and 30th as two depressions passed close to Scotland, the first to the south and the second to the north. There was much rain overnight on 26th/27th with 50 mm measured at Sloy. Winds gusted to 66 m.p.h. at Kirkwall the next day.

The month ended with a ridge of high pressure giving a sunny day on the 31st with the temperature falling to 0 °C at Tulloch Bridge.

Northern Ireland diary of highlights

Mostly dry and warm at first, soon turning unsettled. Often warm and humid - several significant rainfall events.

The first week, apart from some well scattered showers, was often dry and warm with maximum temperatures frequently in the range 23 to 25 °C.

From the 8th onwards, the weather became more unsettled. The remains of ex-hurricane 'Alex' produced a wet day in places with 10-15 mm of rain in many places and 30 mm or more over some parts of County Down.

The second week continued very humid with some very warm sunshine at times but also with some locally heavy, thundery showers. Thundery showers produced 42 mm of rain at Hillsborough, County Down on the 10th.

By the 16th another ex-hurricane, this time 'Bonnie' was making its presence felt, and this low pressure area dominated for the next two or three days. Heavy, thundery downpours occurred on the 17th and Londonderry city centre was badly flooded. Further heavy spells of rain followed on the 18th with a further 20-25 mm of rain in places. Two day rainfall totals from this system brought 35 mm or more in some areas.

The 20th and 21st were temporarily drier and brighter with some good sunny spells and pleasantly warm by day though much cooler at night.

Wet weather resumed on the 22nd & 23rd with a further 25-35 mm in some eastern areas, this time courtesy of ex-hurricane 'Charley'.

By the 24th, the remnants of this low lay right across Northern Ireland and torrential thundery downpours brought flooding to parts of Down and Antrim. 31 mm was recorded in just 90 minutes at Ballyclare on the morning of the 24th.

The remainder of the week was rather unsettled with further rain or showers at times and it was occasionally quite breezy, although there were some brighter and drier interludes for most areas. On the night of the 30th into the 31st clear conditions combined with a northerly airflow allowed temperatures to dip quite low, with Katesbridge recording a minimum of 0.8 °C.

The localised nature of thunderstorms during the month meant there were large variations in rainfall amounts, in some parts these thunderstorms gave nearly 50% of the monthly average in just a couple of hours.

Last updated: 27 February 2013