Weather in Northern Ireland: Temperate Oceanic, Changeable, Green
Climate Classification
Köppen Cfb — Temperate Oceanic. Mild winters, cool summers, no dry season. Gulf Stream + prevailing SW winds = **maritime thermostat**.
Seasonal Breakdown
| Season | Temp Range | Character |
|---|
| Winter (Dec–Feb) | 4–6°C (39–43°F) | Cold, wet, overcast; short days. Snow rare at sea level; regular in Sperrins/Mournes. |
| Spring (Mar–May) | 8–14°C (46–57°F) | Changeable, showers, increasing sun. "Four seasons in a day." |
| Summer (Jun–Aug) | 14–16°C (57–61°F) | Mild, variable; warm spells (20–25°C) possible. Long days (17h solstice). |
| Autumn (Sep–Nov) | 10–14°C (50–57°F) | Similar to spring; "Indian summer" warm spells. Storm season begins. |
Rainfall Gradient
- Wettest: Mourne & Sperrin Mountains — **>2,000 mm/yr** (orographic lift).
- Driest: Lough Neagh basin, North Coast — **<1,000 mm/yr** (rain shadow).
- Pattern: Frequent **drizzle / light rain** (150–200+ rain days/yr) — not torrential.
Extremes (Records)
- Highest: 30.8°C (87.4°F) — Belfast, 12 July 1983.
- Lowest: −17.5°C (0.5°F) — Omagh, Jan 1887.
Climate Change Trajectory
- Winters: **Milder, wetter** — more flooding.
- Summers: **Warmer, possibly drier** — heatwave risk (2021: 31.3°C Castlederg).
- Storms: **More intense** (ex-hurricanes: Ophelia 2017, Lorenzo 2019).
- Sea level: **Rising** — coastal erosion, saline intrusion.
Daily Life Adaptation
- Layered clothing essential.
- Waterproof jacket = daily carry.
- Vitamin D supplementation common (low winter sun).
- Gardening: long season, slugs love it.
Wanderlust World