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| Casement 1971–2000 averages
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| TEMPERATURE (degrees Celsius) | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Year |
| mean daily max | 7.8 | 8.1 | 9.9 | 11.9 | 14.8 | 17.5 | 19.7 | 19.4 | 16.9 | 13.5 | 10.0 | 8.5 | 13.2 |
| mean daily min | 2.0 | 2.2 | 3.1 | 3.8 | 6.2 | 9.0 | 11.3 | 10.9 | 9.1 | 6.9 | 3.9 | 2.9 | 5.9 |
| mean temperature | 4.9 | 5.1 | 6.5 | 7.8 | 10.5 | 13.2 | 15.5 | 15.1 | 13.0 | 10.2 | 7.0 | 5.7 | 9.5 |
| absolute max. | 15.4 | 15.9 | 18.1 | 21.3 | 24.7 | 27.6 | 29.8 | 30.5 | 25.4 | 21.3 | 17.7 | 15.4 | 30.5 |
| min. maximum | -3.0 | -0.7 | 0.7 | 4.3 | 7.1 | 9.2 | 10.6 | 11.7 | 10.4 | 6.8 | 2.1 | -1.1 | -3.0 |
| max. minimum | 11.3 | 13.0 | 11.3 | 12.3 | 13.8 | 16.9 | 17.8 | 18.3 | 17.8 | 16.4 | 13.8 | 12.7 | 18.3 |
| absolute min. | -12.4 | -8.0 | -7.8 | -5.5 | -3.0 | 0.3 | 2.5 | 2.5 | -0.3 | -4.1 | -6.2 | -9.7 | -12.4 |
| mean num. of days with air frost | 7.7 | 6.2 | 4.7 | 3.9 | 0.8 | 0.0 | 0.0 | 0.0 | 0.0 | 1.2 | 5.0 | 6.2 | 35.8 |
| mean num. of days with ground frost | 15.0 | 13.0 | 12.0 | 12.0 | 5.0 | 1.0 | 0.0 | 0.0 | 1.0 | 4.0 | 10.0 | 12.0 | 85.0 |
| mean 5cm soil | 3.6 | 3.3 | 4.5 | 7.3 | 11.3 | 14.9 | 16.4 | 15.2 | 12.4 | 9.2 | 5.5 | 4.5 | 9.0 |
| mean 10cm soil | 3.9 | 3.5 | 4.6 | 7.0 | 10.7 | 14.1 | 15.7 | 14.8 | 12.2 | 9.3 | 5.8 | 4.7 | 8.8 |
| mean 20cm soil | 4.5 | 4.2 | 5.3 | 7.4 | 10.7 | 14.1 | 15.8 | 15.2 | 13.0 | 10.2 | 6.7 | 5.3 | 9.4 |
| RELATIVE HUMIDITY (%) | | | | | | | | | | | | | |
| mean at 0900UTC | 86.6 | 85.6 | 83.9 | 80.2 | 77.1 | 77.9 | 79.2 | 81.3 | 84.1 | 86.0 | 87.6 | 87.3 | 83.1 |
| mean at 1500UTC | 81.7 | 77.1 | 71.8 | 68.0 | 67.5 | 68.1 | 68.2 | 68.7 | 71.4 | 76.4 | 81.0 | 83.4 | 73.6 |
| SUNSHINE (hours) | | | | | | | | | | | | | |
| mean daily duration | 1.6 | 2.4 | 3.0 | 4.7 | 5.7 | 5.3 | 4.9 | 4.8 | 4.1 | 3.1 | 2.1 | 1.4 | 3.6 |
| greatest daily duration | 8.1 | 9.2 | 10.9 | 13.1 | 15.4 | 16.0 | 15.4 | 14.4 | 12.3 | 10.1 | 8.2 | 6.9 | 16.0 |
| mean num. of days with no sun | 10.0 | 6.5 | 4.6 | 2.4 | 1.9 | 1.9 | 1.5 | 1.6 | 2.7 | 4.4 | 7.3 | 10.5 | 55.4 |
| RAINFALL (mm) | | | | | | | | | | | | | |
| mean monthly total | 67.8 | 49.7 | 51.7 | 51.5 | 55.9 | 58.5 | 48.1 | 65.9 | 63.1 | 69.4 | 66.2 | 76.0 | 723.9 |
| greatest daily total | 30.0 | 23.0 | 26.5 | 38.7 | 29.8 | 97.5 | 44.7 | 89.3 | 51.1 | 40.2 | 82.0 | 46.8 | 97.5 |
| mean num. of days with >= 0.2mm | 18 | 15 | 17 | 14 | 15 | 15 | 14 | 15 | 15 | 16 | 16 | 16 | 186 |
| mean num. of days with >= 1.0mm | 13 | 11 | 11 | 10 | 10 | 10 | 9 | 10 | 10 | 12 | 11 | 12 | 129 |
| mean num. of days with >= 5.0mm | 4 | 3 | 3 | 3 | 3 | 3 | 2 | 4 | 4 | 4 | 4 | 5 | 42 |
| WIND (knots) | | | | | | | | | | | | | |
| mean monthly speed | 14.1 | 13.2 | 12.8 | 10.0 | 9.1 | 8.8 | 8.9 | 8.9 | 10.0 | 11.3 | 12.3 | 13.6 | 11.1 |
| max. gust | 80 | 78 | 71 | 59 | 63 | 53 | 58 | 55 | 69 | 65 | 68 | 82 | 82 |
| max. mean 10-minute speed | 57 | 54 | 47 | 43 | 43 | 36 | 39 | 36 | 46 | 44 | 49 | 57 | 57 |
| mean num. of days with gales | 5.2 | 3.1 | 2.5 | 0.5 | 0.5 | 0.1 | 0.1 | 0.2 | 0.5 | 1.3 | 2.5 | 4.2 | 20.7 |
| WEATHER (mean no. of days with..) | | | | | | | | | | | | | |
| snow or sleet | 4.6 | 3.7 | 3.0 | 1.3 | 0.2 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.4 | 2.0 | 15.1 |
| snow lying at 0900UTC | 2.3 | 1.2 | 0.4 | 0.1 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.1 | 0.5 | 4.7 |
| hail | 0.8 | 1.2 | 2.7 | 2.3 | 1.4 | 0.5 | 0.1 | 0.1 | 0.3 | 0.1 | 0.7 | 0.6 | 10.8 |
| thunder | 0.0 | 0.1 | 0.2 | 0.4 | 1.0 | 0.9 | 0.8 | 0.9 | 0.4 | 0.2 | 0.1 | 0.1 | 5.0 |
| fog | 2.2 | 1.7 | 1.5 | 2.4 | 1.6 | 1.2 | 1.2 | 2.4 | 2.9 | 2.3 | 1.8 | 2.2 | 23.3 |