01Fresh mornings and long descents
At the cool end of summer, a normal jersey with arm and knee warmers is the most flexible setup: they come off once you are warm and fit in a back pocket. On an Alpine descent or an early start, a gilet or packable jacket does the same job for your chest.
02Kit for the heat
The lightest, thinnest jersey you own, ideally light-coloured and with a full-length zip so you can open it on climbs. Bib shorts, summer socks, and fingerless gloves only if you like them for grip. A thin cycling cap under the helmet keeps sun off your head and sweat out of your eyes.
03Drink and plan
From a feels-like temperature of 27°C (81°F), kitcheck.cc adds a heat note: take an extra bottle and put on sunscreen. Put electrolytes in at least one bottle, plan a café or water stop on longer rides, and start early in the morning or ride late in the afternoon, when it's cooler.
Ride a notch easier than usual on the climbs. Your body has to work harder to cool down, and pushing your normal pace in the heat costs more than it gives.
04Sun and summer rain
Sunscreen on your arms, legs, neck and the backs of your knees, and reapply it on long rides. Sunglasses help against glare and keep insects out of your eyes.
A summer shower needs no more than a packable rain jacket, and once it is properly warm kitcheck.cc lists even that as optional: you warm up quickly and a wet summer jersey dries fast.