Weather in South London during July 2009
There were only 5 completely dry days during this changeable, wet and rather cool month.
Temperatures
The average maximum temperature was 22.1 Celsius (72F), and that was 1.2 degrees Celsius (2F) below the 20-year normal, and 0.4 degrees Celsius below the 100-year normal. The average minimum temperature was 13.5 Celsius (56F), and that was very close to normal.
The highest temperature recorded during July was 28.9 Celsius (84F), on both the 1st and 2nd, but the 3rd and 4th were the only other days when maxima exceeded 24 Celsius (75F). There were 7 days when the temperature failed to rise above 20 Celsius (68F), including 3 consecutive days commencing on the 7th. The coolest day was the 9th with a high of 18.8 Celsius (66F).
The minimum temperature on the night of the 2nd/3rd was 18.3 Celsius (65F), but after the first 3 nights of the month, the 16th/17th with 15.1 Celsius (59F) was the only night when the temperature remained above 15 Celsius. Although the temperature fell below 12 Celsius (54F) on 8 nights, only one of these nights had a minimum below 11 Celsius (52F), the 9th/10th with a low of 10.7 Celsius (51F)
Frost
There were no air or grass frosts during July. A grass minimum of 3.4 celsius (38F) occurred on the night of the 30th/31st with 2 other nights when the grass reading was below 5 Celsius (41F).
Rain
A total of 62.5 millimetres (2.5ins) of rain fell during July, and that was over 40% above the long-term average. Unusually for a summer month there were only 5 completely dry days. Measurable rain fell on 20 days, 9 above average, and a new station record for July in this part of London. There were 11 wet days (1.0mm/0.04 ins, or more) and that was 4 days above average. Rainfall was generally light, and there were only 4 days when the total exceeded 5 millimetres (0.2ins). The 2nd, 7th, 11th and 16th. On the 7th nearly 11 millimetres (0.4ins) of rain fell, but the wettest day was the 16th with 13.8 millimetres (0.54ins).
Thunderstorms
In this unsettled month, thunderstorms occurred with above average frequency. In South London, there were 4 days with thunder, 1 above average. On the 3rd, there was a short-lived thunderstorm before dawn. On the 7th, there were 3 separate storms in the afternoon and early evening with some heavy rain. Further bursts of heavy rain accompanied thunderstorms that rumbled on through much of the evening on 16th. There were 2 storms on the afternoon of the 24th, but rainfall was light.
Hail
No hail was observed in this part of South London.
Snow
None reported.
Wind
Gentle easterly winds blew on the first 2 days of the month, otherwise moderate west to southwesterly breezes predominated. Days were often unpleasantly blustery, with gusts frequently exceeding 20 knots (23mph). The highest gust was 28 knots (32mph) on the 19th.
Fog
None reported in this part of London.
Monthly figures for July in, and around, London
The average maximum temperature was 22.1 Celsius (72F), and that was 1.2 degrees Celsius (2F) below the 20-year normal, and 0.4 degrees Celsius below the 100-year normal. The average minimum temperature was 13.5 Celsius (56F), and that was very close to normal.
The highest temperature recorded during July was 28.9 Celsius (84F), on both the 1st and 2nd, but the 3rd and 4th were the only other days when maxima exceeded 24 Celsius (75F). There were 7 days when the temperature failed to rise above 20 Celsius (68F), including 3 consecutive days commencing on the 7th. The coolest day was the 9th with a high of 18.8 Celsius (66F).
The minimum temperature on the night of the 2nd/3rd was 18.3 Celsius (65F), but after the first 3 nights of the month, the 16th/17th with 15.1 Celsius (59F) was the only night when the temperature remained above 15 Celsius. Although the temperature fell below 12 Celsius (54F) on 8 nights, only one of these nights had a minimum below 11 Celsius (52F), the 9th/10th with a low of 10.7 Celsius (51F)
Frost
There were no air or grass frosts during July. A grass minimum of 3.4 celsius (38F) occurred on the night of the 30th/31st with 2 other nights when the grass reading was below 5 Celsius (41F).
Rain
A total of 62.5 millimetres (2.5ins) of rain fell during July, and that was over 40% above the long-term average. Unusually for a summer month there were only 5 completely dry days. Measurable rain fell on 20 days, 9 above average, and a new station record for July in this part of London. There were 11 wet days (1.0mm/0.04 ins, or more) and that was 4 days above average. Rainfall was generally light, and there were only 4 days when the total exceeded 5 millimetres (0.2ins). The 2nd, 7th, 11th and 16th. On the 7th nearly 11 millimetres (0.4ins) of rain fell, but the wettest day was the 16th with 13.8 millimetres (0.54ins).
Thunderstorms
In this unsettled month, thunderstorms occurred with above average frequency. In South London, there were 4 days with thunder, 1 above average. On the 3rd, there was a short-lived thunderstorm before dawn. On the 7th, there were 3 separate storms in the afternoon and early evening with some heavy rain. Further bursts of heavy rain accompanied thunderstorms that rumbled on through much of the evening on 16th. There were 2 storms on the afternoon of the 24th, but rainfall was light.
Hail
No hail was observed in this part of South London.
Snow
None reported.
Wind
Gentle easterly winds blew on the first 2 days of the month, otherwise moderate west to southwesterly breezes predominated. Days were often unpleasantly blustery, with gusts frequently exceeding 20 knots (23mph). The highest gust was 28 knots (32mph) on the 19th.
Fog
None reported in this part of London.
Monthly figures for July in, and around, London
| Place | Maximum | Minimum | Rainfall (mm) |
| C. London | 29.5 | 11.5 | 66 |
| Heathrow A/P | 30.9 | 10.8 | 71 |
| Gatwick A/P | 30.5 | 9.1 | 82 |
| Croydon | 27.6 | 9.2 | 79 |
| Northolt | 29.8 | 9.1 | 95 |
| Farnborough | 30.3 | 8.5 | 72 |
| Stansted A/P | 27.5 | 8.5 | 40 |