One of them waterproof............If you're in Ayrshire, turn the central heating down a notch. Two layers for cycling should be enough.
The Met Office have issued a heat wave warning.
Don't forget that if you've got to be out and about, particularly if you're cycling, you should have sunscreen on, you're covered up and carry water. If you have elderly neighbours, do the nice thing and check they're OK.
The NHS is already under strain and can't afford to have additional A&E attendance though dehydration, sunstroke and heat exhaustion.
As the Aussies and Kiwis would say: Slip, Slop, Slap
Goes without saying!One of them waterproof............