Belfast vs Castletown: which is sunnier?
🇬🇧 United Kingdom vs 🇮🇲 Isle of Man · 121 km apart · long-term climate normals (NASA POWER, 2001–2020)
Castletown is the sunnier overall: about 1,459 hours of sunshine a year to Belfast's 1,263. Belfast has the higher Sunshine Score in 6 of 12 months, Castletown in 3 (3 within 2 points).
Scores are the 0–100 Sunshine Score — sunshine, daytime warmth and dryness in one number, per month.
At a glance
| Belfast | Castletown | |
|---|---|---|
| Sunshine hours / year | 1,263 | 1,459 |
| Sunniest month | July (56/100) | July (48/100) |
| Nov–Feb average score | 2/100 | 5/100 |
| Jun–Aug average score | 54/100 | 44/100 |
| Rain / year | 1,068 mm | 1,123 mm |
| Peak midday UV | 4 (moderate) | 5 (moderate) |
Belfast vs Castletown month by month
| Month | Sunshine Score | Day high °C | Rain mm | |||
|---|---|---|---|---|---|---|
| Belfast | Castletown | Belfast | Castletown | Belfast | Castletown | |
| January | 0 | 0 | 6° | 8° | 93 | 110 |
| February | 0 | 0 | 7° | 8° | 74 | 89 |
| March | 0 | 0 | 8° | 8° | 76 | 82 |
| April | 19 | 6 | 11° | 9° | 62 | 62 |
| May | 36 | 25 | 14° | 12° | 77 | 65 |
| June | 52 | 37 | 17° | 14° | 90 | 74 |
| July | 56 | 48 | 18° | 16° | 99 | 79 |
| August | 55 | 46 | 18° | 16° | 106 | 97 |
| September | 47 | 41 | 16° | 15° | 82 | 90 |
| October | 27 | 32 | 13° | 14° | 109 | 123 |
| November | 6 | 16 | 9° | 11° | 105 | 126 |
| December | 0 | 5 | 7° | 9° | 95 | 126 |
The sunnier month by month: Jan even · Feb even · Mar even · Apr Belfast · May Belfast · Jun Belfast · Jul Belfast · Aug Belfast · Sep Belfast · Oct Castletown · Nov Castletown · Dec Castletown.
When to pick which
- November–February: Castletown (average score 5/100 vs 2). Castletown is the warmer, around 9°C daytime highs vs 7°C. See the winter sun ranking.
- March–May: Belfast (average score 18/100 vs 10). Daytime highs are similar (11°C vs 10°C).
- June–August: Belfast (average score 54/100 vs 44). Belfast is the warmer, around 18°C daytime highs vs 15°C.
- September–October: too close to call — Belfast averages 37/100, Castletown 37/100. Daytime highs are similar (15°C vs 15°C).
Full month-by-month guides: Belfast weather by month · Castletown weather by month · Best time to visit United Kingdom.
More comparisons: Belfast vs Glasgow · Belfast vs Glasgow · Belfast vs Dublin · Castletown vs Dublin · Castletown vs Liverpool · all head-to-heads