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| Belmullet 1961-1990 averages | | | | | | | | | | | | | |
| TEMPERATURE (degrees Celsius) | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Year |
| mean daily max. | 8.2 | 8.3 | 9.7 | 11.6 | 13.7 | 15.7 | 16.8 | 17.2 | 15.7 | 13.4 | 10.3 | 9.0 | 12.5 |
| mean daily min. | 3.1 | 2.9 | 3.9 | 4.9 | 7.0 | 9.5 | 11.1 | 11.1 | 9.8 | 8.2 | 5.1 | 4.3 | 6.7 |
| mean | 5.7 | 5.6 | 6.8 | 8.2 | 10.3 | 12.6 | 14.0 | 14.1 | 12.8 | 10.8 | 7.7 | 6.6 | 9.6 |
| absolute max. | 13.0 | 13.8 | 19.4 | 23.3 | 26.0 | 27.0 | 28.7 | 27.4 | 22.4 | 22.1 | 15.2 | 13.5 | 28.7 |
| absolute min. | -8.1 | -6.3 | -5.7 | -2.6 | -0.4 | 1.4 | 5.1 | 3.1 | 0.8 | -0.7 | -2.5 | -5.2 | -8.1 |
| mean no. of days with air frost | 5.0 | 4.3 | 2.1 | 0.9 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.1 | 1.3 | 3.1 | 16.7 |
| mean no. of days with ground frost | 10.5 | 9.5 | 7.3 | 5.4 | 1.9 | 0.1 | 0.0 | 0.0 | 0.5 | 1.7 | 5.5 | 7.8 | 50.3 |
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| RELATIVE HUMIDITY (%) | | | | | | | | | | | | | |
| mean at 0900UTC | 85 | 84 | 82 | 80 | 78 | 81 | 85 | 85 | 84 | 85 | 85 | 85 | 83 |
| mean at 1500UTC | 81 | 77 | 75 | 73 | 73 | 77 | 80 | 79 | 78 | 80 | 80 | 83 | 78 |
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| SUNSHINE (hours) | | | | | | | | | | | | | |
| mean daily duration | 1.47 | 2.41 | 3.29 | 5.27 | 6.14 | 5.36 | 4.29 | 4.63 | 3.65 | 2.63 | 1.74 | 1.08 | 3.50 |
| greatest daily duration | 7.9 | 9.8 | 11.2 | 14.0 | 15.6 | 15.8 | 15.4 | 14.0 | 12.5 | 9.8 | 8.1 | 6.7 | 15.8 |
| mean no. of days with no sun | 10 | 6 | 5 | 3 | 2 | 3 | 3 | 3 | 4 | 6 | 8 | 12 | 66 |
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| RAINFALL (mm) | | | | | | | | | | | | | |
| mean monthly total | 123.5 | 80.1 | 95.8 | 58.1 | 68.0 | 67.3 | 67.6 | 93.7 | 108.0 | 132.9 | 127.7 | 119.9 | 1142.7 |
| greatest daily total | 32.2 | 23.6 | 25.9 | 20.4 | 26.5 | 35.2 | 44.9 | 57.3 | 56.1 | 67.8 | 56.4 | 40.5 | 67.8 |
| mean no. of days with >= 0.2mm | 23 | 19 | 23 | 19 | 18 | 18 | 19 | 20 | 21 | 24 | 23 | 24 | 249 |
| mean no. of days with >= 1.0mm | 20 | 15 | 18 | 13 | 14 | 12 | 12 | 15 | 16 | 19 | 19 | 19 | 193 |
| mean no. of days with >= 5.0mm | 9 | 6 | 7 | 4 | 5 | 4 | 4 | 6 | 7 | 9 | 9 | 9 | 80 |
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| WIND (knots) | | | | | | | | | | | | | |
| mean monthly speed | 14.7 | 13.9 | 14.2 | 12.2 | 12.4 | 11.9 | 11.6 | 11.3 | 13.0 | 14.3 | 13.6 | 14.3 | 13.1 |
| max. gust | 91 | 93 | 88 | 67 | 69 | 73 | 67 | 60 | 84 | 85 | 76 | 89 | 93 |
| max. mean 10-minute speed | 58 | 61 | 58 | 43 | 47 | 47 | 45 | 44 | 57 | 58 | 50 | 60 | 61 |
| mean no. of days with gales | 5.5 | 4.2 | 3.3 | 1.1 | 1.0 | 0.4 | 0.3 | 0.8 | 2.3 | 3.6 | 3.4 | 4.5 | 30.5 |
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| WEATHER (mean no. of days with...) | | | | | | | | | | | | | |
| snow or sleet | 4.6 | 4.4 | 4.0 | 1.6 | 0.2 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.7 | 2.6 | 18.1 |
| snow lying at 0900UTC | 0.8 | 0.6 | 0.3 | 0.1 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.4 | 2.3 |
| hail | 8.5 | 6.2 | 7.4 | 4.0 | 1.9 | 0.2 | 0.1 | 0.1 | 0.5 | 2.8 | 6.7 | 6.7 | 45.1 |
| thunder | 0.9 | 0.6 | 0.5 | 0.3 | 0.4 | 0.5 | 0.6 | 0.2 | 0.2 | 0.2 | 0.4 | 0.6 | 5.5 |
| fog | 1.1 | 0.6 | 0.7 | 1.7 | 1.3 | 2.0 | 3.3 | 2.4 | 1.1 | 1.2 | 0.6 | 0.6 | 16.6 |