Britain has a temperate maritime climate: mild winters, cool summers, rainfall spread through the year, and very little in the way of extremes. What makes this remarkable is the latitude at which it happens.
The latitude problem
Britain sits between about 50° and 60° north. That puts London level with Calgary, Edinburgh level with Moscow, and Shetland level with southern Greenland. On latitude alone, Britain should have hard continental winters with months of frozen ground.
It does not, because of the North Atlantic Current — the northern extension of the Gulf Stream — which carries warm surface water from the Caribbean across the Atlantic and past Britain’s western coasts. Combined with prevailing south-westerly winds blowing over that warm water, it lifts British temperatures perhaps 5-10°C above what the latitude would otherwise give.
The practical result: palm trees grow in Cornwall and western Scotland at latitudes where Canada has permafrost.
The regional pattern
Britain is small but climatically varied, and the pattern runs diagonally:
- West and north-west — wettest. Air blowing off the Atlantic is forced up over the hills of Wales, the Lake District and western Scotland, cooling and dropping its moisture. Seathwaite in Cumbria receives over 3,500mm a year.
- East and south-east — driest, sitting in the rain shadow of those uplands. Parts of Essex and Cambridgeshire get under 600mm, less than Jerusalem, and East Anglia has genuine water scarcity.
- South — warmest, with the Isles of Scilly effectively frost-free.
- North and upland — coolest, with snow lying for weeks on the Cairngorms.
The upshot is that the difference between Cornwall and Caithness is considerable, and national weather generalisations are usually wrong for somewhere.
Why it changes so quickly
Britain sits at the boundary of several competing air masses — polar and tropical, maritime and continental — on the eastern edge of an ocean and the western edge of a continent. Depressions track across it from the Atlantic in a near-continuous procession.
This is why British weather is genuinely difficult to forecast beyond a few days, and why “four seasons in one day” is a fair description rather than an exaggeration.
A changing climate
Britain is warming measurably. The ten warmest years on record have all occurred since 2002, and 40.3°C was recorded at Coningsby in Lincolnshire in July 2022 — the first time 40 degrees had ever been reached in the UK.
The observed and projected effects are: hotter, drier summers; warmer, wetter winters; more intense rainfall events and consequent flooding; and rising sea levels around a coastline with a great deal of low-lying land in East Anglia and around the Thames.
The heat is the harder adaptation problem. British buildings are designed to retain warmth, air conditioning is rare in homes, railway tracks buckle, and the country handles 35°C considerably worse than places accustomed to it.