| Average climate data for Saint Johns, Isle of Man | |||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Month | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Year |
| Average maximum temperature (°C) | 8 | 7 | 8 | 9 | 12 | 14 | 16 | 16 | 15 | 13 | 11 | 9 | 16 |
| Average minimum temperature (°C) | 6 | 5 | 6 | 7 | 9 | 12 | 13 | 14 | 13 | 11 | 9 | 7 | 5 |
| Average precipitation (mm) | 38 | 33 | 36 | 24 | 24 | 43 | 41 | 52 | 37 | 51 | 63 | 52 | 494 |
| Average rainfall days (days) | 16 | 13 | 13 | 13 | 13 | 14 | 18 | 17 | 14 | 18 | 19 | 18 | 185 |
| Average snowfall (mm) | 3 | 12 | 16 | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 5 | 10 | 47 |
| Average snowfall days (days) | 1 | 1 | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 1 | 5 |
| Average relative humidity (%) | 78 | 80 | 79 | 79 | 81 | 83 | 84 | 83 | 81 | 79 | 76 | 80 | 80 |
| Average wind speed (km/h) | 33 | 31 | 27 | 23 | 23 | 20 | 20 | 24 | 27 | 29 | 33 | 35 | 27 |
| Average daily daylight hours (h) | 8 | 9 | 11 | 14 | 16 | 17 | 16 | 14 | 12 | 10 | 8 | 7 | 12 |
| Average daily sunshine hours (h) | 3 | 3 | 5 | 8 | 8 | 8 | 8 | 7 | 7 | 4 | 3 | 3 | 6 |
| Average cloud coverage (%) | 64 | 59 | 55 | 47 | 45 | 50 | 49 | 52 | 53 | 59 | 60 | 63 | 55 |
| Average UV index | 2 | 2 | 2 | 3 | 4 | 4 | 4 | 4 | 4 | 3 | 3 | 3 | 3 |
The warmest month, with the highest average maximum temperature, is August (15.9 °C). The month with the lowest average maximum temperature is February (7.4 °C). Overall, the average maximum temperature over the whole year is 11.6 °C.
The month with the highest average minimum temperature is August (13.9 °C). The coldest month, with the lowest average minimum temperature, is February (5.1 °C). Overall, the average minimum temperature over the whole year is 9.4 °C.
The wettest month, with the highest amount of precipitation, is November (63.2 mm). The driest month, with the least amount of precipitation, is May (23.9 mm). Over the whole year there are 493.9 mm of rainfall on average.
The month with the most days of rain is November (19.5 days). The month with the fewest days of rain is May (12.6 days). Over the whole year there are 185.2 days of rain on average.
The month with the most snowfall is March (16 mm). The months with the least snowfall are May, June, July, August, September and October (0 mm). Over the whole year there are 47 mm of snowfall on average.
The month with the most days of snowfall is February (1.3 days). The months with the fewest days of snowfall are July, September and October (0 days). Over the whole year there are 5.5 days of snowfall on average.
The month with the highest average relative humidity is July (84.1 %). The month with the lowest average relative humidity is November (75.8 %). The overall average relative humidity over the whole year is 80.2 %.
The windiest month, with the highest average wind speed, is December (34.7 km/h). The calmest month, with the lowest average wind speed, is June (19.8 km/h). The overall average wind speed over the whole year is 27 km/h.
The month with the cloudiest skies, so the highest cloud coverage, is January (64.1 %). The month with the clearest skies, so the lowest cloud coverage, is May (44.8 %). Over the whole year there is an average cloud coverage of 54.7 %.
The month with the longest days, so the most daylight, is June (Average daylight: 17 h). The month with the shortest days, so the least daylight, is December (Average daylight: 7 h). Over the whole year there are 11.9 h of daylight per day on average.
The month with the most sunshine per day is June (Average sunshine: 8.1 h). The month with the least sunshine per day is December (Average sunshine: 3 h). Over the whole year there are 5.6 h of sunlight per day on average.
The months with the highest average UV index are May, June, July, August and September (UV index: 4). The months with the lowest average UV index are January, February and March (UV index: 2). Over the whole year the average UV index is 3.2.
