25/06/2026 – Weather in Cornwall

Cornwall heads for 32C before thunderstorms move in overnight

If you are in Cornwall today, get ready to sweat. The mercury is set to hit 32C, with extreme heat and high humidity hanging around well into the afternoon. And the heat does not break quietly. Overnight, thunderstorms move in.

Today: extreme heat and high humidity

It starts dry, warm and sunny. From there it only climbs. Forecasters expect extreme heat to build through the day, with high humidity making it feel sticky on top of the raw temperature. Some high cloud may drift in at times during the afternoon, but it does little to take the edge off. The high reaches 32C.

Tonight: thunderstorms, gusts and possible hail

The warmth does not let up after dark. It stays very warm and humid overnight, with the minimum only dropping to 17C.

The bigger change is what comes with it. Elevated thunderstorms spread northwards, turning very gusty, with the odd rumble of thunder and the chance of hail. Low cloud also moves into Cornwall.

Friday: cooler, but still very warm

Temperatures start to come down on Friday, though “down” is relative. It stays very warm and humidity remains high. The cloud across Cornwall lifts through the morning, leaving plenty of strong sunshine for everyone. The high settles at 29C.

The weekend and beyond

It stays hot into the weekend before temperatures slowly ease off by Sunday. Most places stay dry, with things turning cloudier as the new week begins.