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The Weather at Durham in 2001

The Weather at Durham in 2001

Temperatures in January were virtually average. The absolute maximum of 8.3°C was fairly low, the lowest since 1980. The absolute minimum was well within the usual range and, whilst quite a high figure, 23 ground frosts was also within the normal range. January was slightly drier than average with 86.6% of the average amount of precipitation. Rain was well spread out through the month. The 3-monthly running total remained high at 269.4mm, but not as high as the very high November and December 2000 figures. The 6-monthly running total was also very high, but lower than November. There were some snow showers but these are no longer officially observed so no data are available. It was a sunny January, with 35% more sunshine recorded than average. Wind speed was below average.

The mean temperature in February was just above average at 3.5­. This was achieved with a mean daily maximum well above average because the mean daily minimum was well below. It was a very wet February with 90.2mm of precipitation, more than twice the average. This made it the wettest February since 1966 and the 5th wettest February on record since 1852; the wettest February remains 1941 with 152.5mm. The 3-monthly running rainfall total of 208.8mm was high but lower than January’s as the very wet November figure dropped out of the calculation. However, the 6-monthly running total was exceptionally high at 563.6mm (not far off the annual average!). This is the highest six-monthly running figure for a February (i.e. autumn plus winter total) since February 1977 when the total was 574.1mm. The figure of 563.6 ranks 5th highest since records began in 1852; apart from 1977, the other three higher totals all come from the 1870s, which is well known as having been a very wet decade: 1875 (567.6), 1873 (687.2) and 1877 (755.8). Despite the high rainfall February was also very sunny, 51.5% above average. Although rain fell on 18 days, the bulk fell between the 2nd and 8th (64mm) and in this period there were only 9.9 hours of sunshine.

March was cooler than average due to the mean daily maximum of 7.2°C being well below the average of 8.4. Absolute temperatures were well within the usual range but at -4.4°C the absolute minimum was the lowest since 1994 (-8.5­C)ž There were 21 ground frosts, 2 more than in February. Rainfall was slightly above average but was substantially higher than in 2000. Hence, the 12-running rainfall total was higher than February’s and so March’s figure (994.4mm) created another record.

April was slightly cooler than average, also duller and slightly wetter. Rainfall was 23.4% above average but since the total of 59mm was much lower than April 2000’s enormous figure of 150mm, the 12-month running rainfall total dropped substantially, although still standing above 900mm for the third month in a row.

May had temperatures above average with great extremes; the range was 28.9 degrees between absolute maximum and minimum. The absolute maximum of 29°C (84.2F) was the highest such figure for May on the record back to 1847 with the record before this held by 31st May 1922 at 82F. It was also the hottest day in Durham since August 1997 when 29.5°C (85.1F) was reached. It was also a very dry May with only 7.8mm of precipitation recorded; this is the driest May since 1989 (7.7mm). It was also the driest month in Durham since February 1998 (6.1mm). This total brought the 3-monthly running rainfall total to below average; the 6-monthly figure remained somewhat above average, whilst the 12-monthly total had now fallen to 866mm – still well above 1961-90 average (649mm). Sunshine figures in May were, unsurprisingly, very high. The total of 229.6 hours was the highest May figure since 1989 (246 hours). High pressure dominated the weather for much of May bringing stable, calm and therefore dry conditions, together with increasingly warm temperatures late in the month.

Temperatures in June were very close to average and the range was more limited than May’s. After a warm start the month was cooler in the middle two weeks but the last week, from the 24th, was very warm indeed with 6 days having maxima over 20°C. The last third of June was also rainless, adding to the pleasant feel, although wind speeds were occasionally quite high during the period. Our automatic rain gauge did not function during July (a problem that persisted through until October) so the rainfall data reported here are based on figures supplied by the Environment Agency for nearby Barker Heugh. Estimated rainfall for June was well below average and with a very wet June in 2000 falling out of the calculation, the 12-month running total fell to 813mm. June’s sunshine was disappointing, more than 30 hours below average. Although there were only 3 sunless days, several others around the middle of the month had very low totals. Wind speeds for June were well above average giving a curious feel to some otherwise dry and warm days. Generally high pressure dominated in June with occasional frontal systems bringing windier and showery weather.

July was warmer than average by just over 1°C. There were numerous very warm days: 20­°C was exceeded on 17 days, but nevertheless the absolute maximum was an unspectacular 25.6°­C on the 3rd. It was also a drier month then normal with only 85% of average rainfall.ž Added to a relatively dry June and a very dry May, this meant that the 3-monthly-running rainfall total stood at its lowest July level (88.9mm) since 1995 (71.9) and was the 9th lowest 3-month total for July since 1852. The 6-monthly figure was a little below average, whilst the 12-monthly running rainfall figure still exceeded the annual average by 32mm. It was not a sunny month. There were only 2 days with no sunshine but a relatively meagre total of 114.7 hours was spread quite thinly. Only 3 days had more than 8 hours of sunshine: the 31st, 29th and 3rd. Wind speeds were below average reflecting relatively high pressure and slack pressure gradients. Light northerly winds kept temperatures down in the middle of the month after a very warm start, but the warmth returned in the last 9 days as pressure rose again.

August’s temperatures were very similar to July, as were its lower-than-average rainfall and sunshine. The mean temperature was 1.3­°C above the average, with 20 days when the maximum reached or exceeded 20°­C. The absolute maximum was only 25­°C, however. Sunshine and dry days were well spread through August: sunshine was recorded on all but 2 days and six days had 8 hours sunshine or more. It was a relatively calm month with wind speeds below average, reflecting slack pressure gradients in predominantly high-pressure conditions.

Mean air temperature in September was slightly above the long-term average. Maximum temperatures were disappointing but minima were above average. This suggests a cloudy month, and indeed the mean sunshine figures show a disappointing total, well below the average (by nearly 2 hours per day). Rainfall was above average, but not greatly so.

October was a remarkably warm month, certainly the warmest October in Durham since records began in 1850. The previous warmest October was in 1969 but that was a massive 0.7­°C cooler than October 2001! This continues a most interesting trend in that October has shown a greater warming trend than most other months throughout the 20th century. As expected, both maximum and minimum air temperatures were well above average, and there were no ground or air frosts.

November was, like October, a very warm month, but not quite so exceptionally so. Nevertheless mean air temperature was the 10th warmest on record since 1850, and the warmest since 1997. As expected, both maxima and minima were well above average too. Despite an average September, autumn 2001 as a whole was easily the warmest on record at Durham in over 150 years, an average air temperature of 11.1­C beating the previous record in 1999 by 0.3­°C. Rainfall in November was below average, but so too was sunshine. The large number of rain days (16) perhaps explains this result; no sunshine at all was recorded on 6 days compared to previous months.

December was cooler than normal, particularly at night, and mean air temperature fell half a degree Celsius below the average. With rainfall below average and sunshine above average, this suggests cloud-free weather with sunny days and frosty nights, and there were indeed 23 ground frosts and 17 air frosts. Although there were 17 rain days, none was very wet, with Christmas Eve recording the highest daily total of only 5.6mm.

Given problems with our rain gauge, the annual rainfall total of 566.3mm is only an estimate. However, if correct, this shows a dry year, the driest since 1996, 83mm below average and the 32nd driest year since 1852. If we measure to two decimal places, 2001 was the 13th warmest year on record since 1850, or equal 10th if we round to 9.3­°C! Of the 12 warmer years, 6 have occurred since 1990. Most remarkably, the 10-year average for the 10 years up to and including 2001 is the warmest 10-year period on record at Durham since records began. For the statisticians among the readership, it is notable that this 10-year average (9.10°C) is almost exactly two standard deviations above the long-term mean (8.5­°C). Clearly the last decade has been quite exceptional!

Finally, may I take this opportunity to thank Dr Helen Goldie, who retired from the Department of Geography in September, for all her care and attention over the years in looking after the meteorological records of the Durham University Observatory.

Professor Tim Burt
Department of Geography
Durham University