The estimated averages for Cleadon for 1971-2000 are calculated based on comparisons between my average monthly readings and those of Durham University Observatory, plus close examination of the Met Office long-term average maps. All monthly, seasonal and annual totals and averages are compared with these estimated long-term averages (ELTAs).
| Month | Max temp | Min temp | Mean temp | Precip | Air frost | Thunder | Sleet or snow | Snow lying | Hail | Mean SLP | Wet days |
| Jan | 6.6 | 1.6 | 4.1 | 54 | 10 | 0 | 7 | 4 | 1 | 1011 | 12 |
| Feb | 7.1 | 1.7 | 4.4 | 39 | 9 | 0 | 7 | 3 | 1 | 1013 | 9 |
| Mar | 9.1 | 2.9 | 6.0 | 49 | 6 | 0 | 5 | 1 | 2 | 1013 | 10 |
| Apr | 11.0 | 4.2 | 7.6 | 50 | 3 | 0 | 2 | 0 | 2 | 1014 | 9 |
| May | 13.9 | 6.6 | 10.3 | 51 | 0 | 1 | 0 | 0 | 1 | 1015 | 10 |
| June | 16.7 | 9.5 | 13.1 | 55 | 0 | 2 | 0 | 0 | 0 | 1015 | 10 |
| July | 19.1 | 11.7 | 15.4 | 48 | 0 | 1 | 0 | 0 | 0 | 1015 | 9 |
| Aug | 18.9 | 11.6 | 15.3 | 62 | 0 | 2 | 0 | 0 | 0 | 1015 | 9 |
| Sep | 16.3 | 9.6 | 13.0 | 56 | 0 | 1 | 0 | 0 | 0 | 1014 | 10 |
| Oct | 13.1 | 7.0 | 10.0 | 58 | 1 | 0 | 0 | 0 | 0 | 1012 | 11 |
| Nov | 9.3 | 4.1 | 6.7 | 66 | 4 | 0 | 3 | 1 | 1 | 1010 | 12 |
| Dec | 7.4 | 2.5 | 5.0 | 57 | 8 | 0 | 5 | 2 | 1 | 1010 | 11 |
| Win | 7.0 | 1.9 | 4.5 | 150 | 27 | 0 | 19 | 9 | 3 | 1011.3 | 32 |
| Spr | 11.3 | 4.6 | 8.0 | 150 | 9 | 2 | 7 | 2 | 5 | 1014.0 | 29 |
| Sum | 18.2 | 10.9 | 14.6 | 165 | 0 | 4 | 0 | 0 | 1 | 1015.0 | 28 |
| Aut | 12.9 | 6.9 | 9.9 | 180 | 5 | 2 | 3 | 1 | 2 | 1012.0 | 33 |
| Annual | 12.4 | 6.1 | 9.2 | 645 | 41 | 7 | 29 | 11 | 10 | 1013.1 | 122 |