Weather in South London during April 2009
A dry month and the third warmest since 1900. In this area, only the Aprils of 1943 and 2007 were warmer.
Temperatures
The average maximum temperature was 16.0 Celsius (61F), and that was 1.7 degrees Celsius (3F) above normal. The average minimum temperature was 6.7 Celsius (44F), and that was 1.3 Celsius (2F) above normal.
The highest temperature recorded during April was 20.8 Celsius (69F) on the 21st, and there were 5 other days, 4 of which occurred between the 20th and 24th, when maxima exceeded 18 Celsius (64F). There were only 8 days during April when the temperature failed to rise above 15 Celsius (59F). Most of the cooler days were during the first fortnight of the month, but the 2 coldest days occurred after mid month. On the 17th, the highest temperature was 10.7 Celsius (51F), and on the 27th the maximum was only 10.5 Celsius (51F).
The minimum temperature on the night of the 15th/16th was 11.1 Celsius (52F), and there were 3 other nights, the 9th/10th, 12th/13th and 24th/25th when the minimum value stayed above 10 Celsius (50F). There were only 7 nights when the temperature dipped below 5 Celsius (41F) and, unusually, only 3 nights with minima under 3 Celsius (37F). On the opening night of the month the temperature fell to 0.8 Celsius (33F), but the coldest night was that of the 27th/28th with a low of 0.6 Celsius (33F).
Frost
There were no air frosts during April, and that's 2 fewer than average. There were 7 grass frosts, and that's 3 fewer than average. On 4 nights, the grass minimum fell below minus 2 Celsius (28F), and on 2 nights, values of minus 3.1 Celsius (26F) were recorded. The first night of April, along with that of the 27th/28th produced these lowest readings.
Rain
A total of 28.4 millimetres (1.1ins) of rain fell during April, and that was only just over 50% of the long-term average. Measurable rain fell on 12 days, 2 days below average, with the 7 wet days (1.0mm/0.04 ins, or more) also 2 days below average. The wettest weather occurred around the middle of the month, and the 16th and 17th were the only days during April when rainfall exceeded 5millimetres (0.2 ins). The wettest day was the 17th, when 6.3 millimetres (0.24 ins) was recorded.
Thunderstorms
Thundery rain spread from the south on the 14th, but the only thunder in Morden was one very sharp crack immediately to the southeast late in the evening.Showers on the 28th produced thunder across south London early in the evening.
Hail
None reported.
Snow
None reported.
Wind
Winds were generally light or gentle and mainly between southeast and southwest, but on the first 2 days, and again around mid month, northeasterly breezes predominated. The highest gust for the month was only 26 knots (30mph), this occurring on 8th.
Fog
There was no fog in Morden, but fog developed for a while along the Thames in east London on the evening of the 13th, and on several mornings towards the end of the month fog was reported in the more rural parts of west London.
Monthly figures for April in, and around, London
The average maximum temperature was 16.0 Celsius (61F), and that was 1.7 degrees Celsius (3F) above normal. The average minimum temperature was 6.7 Celsius (44F), and that was 1.3 Celsius (2F) above normal.
The highest temperature recorded during April was 20.8 Celsius (69F) on the 21st, and there were 5 other days, 4 of which occurred between the 20th and 24th, when maxima exceeded 18 Celsius (64F). There were only 8 days during April when the temperature failed to rise above 15 Celsius (59F). Most of the cooler days were during the first fortnight of the month, but the 2 coldest days occurred after mid month. On the 17th, the highest temperature was 10.7 Celsius (51F), and on the 27th the maximum was only 10.5 Celsius (51F).
The minimum temperature on the night of the 15th/16th was 11.1 Celsius (52F), and there were 3 other nights, the 9th/10th, 12th/13th and 24th/25th when the minimum value stayed above 10 Celsius (50F). There were only 7 nights when the temperature dipped below 5 Celsius (41F) and, unusually, only 3 nights with minima under 3 Celsius (37F). On the opening night of the month the temperature fell to 0.8 Celsius (33F), but the coldest night was that of the 27th/28th with a low of 0.6 Celsius (33F).
Frost
There were no air frosts during April, and that's 2 fewer than average. There were 7 grass frosts, and that's 3 fewer than average. On 4 nights, the grass minimum fell below minus 2 Celsius (28F), and on 2 nights, values of minus 3.1 Celsius (26F) were recorded. The first night of April, along with that of the 27th/28th produced these lowest readings.
Rain
A total of 28.4 millimetres (1.1ins) of rain fell during April, and that was only just over 50% of the long-term average. Measurable rain fell on 12 days, 2 days below average, with the 7 wet days (1.0mm/0.04 ins, or more) also 2 days below average. The wettest weather occurred around the middle of the month, and the 16th and 17th were the only days during April when rainfall exceeded 5millimetres (0.2 ins). The wettest day was the 17th, when 6.3 millimetres (0.24 ins) was recorded.
Thunderstorms
Thundery rain spread from the south on the 14th, but the only thunder in Morden was one very sharp crack immediately to the southeast late in the evening.Showers on the 28th produced thunder across south London early in the evening.
Hail
None reported.
Snow
None reported.
Wind
Winds were generally light or gentle and mainly between southeast and southwest, but on the first 2 days, and again around mid month, northeasterly breezes predominated. The highest gust for the month was only 26 knots (30mph), this occurring on 8th.
Fog
There was no fog in Morden, but fog developed for a while along the Thames in east London on the evening of the 13th, and on several mornings towards the end of the month fog was reported in the more rural parts of west London.
Monthly figures for April in, and around, London
| Place | Maximum | Minimum | Rainfall (mm) |
| C. London | 21.1 | 5.5 | 25 |
| Heathrow A/P | 20.7 | 2.0 | 28 |
| Gatwick A/P | 21.1 | -0.2 | 42 |
| Croydon | 20.2 | 2.1 | 38 |
| Northolt | 20.8 | 0.4 | 34 |
| Farnborough | 20.9 | -0.8 | 27 |
| Stansted A/P | 19.0 | 0.6 | 23 |