So far this summer we've had pretty perfect riding weather here in Southern California, but temperatures are starting to warm up. Hot weather doesn't mean you have to forego your ride — it just requires a bit more planning.
1) Ride early or later to avoid peak heat. Mornings tend to be the coolest part of the day, but the hours just before sunset can also be mild.
2) Stay close to the coast or head for the hills. Temperatures in inland valleys are typically the warmest, so ride near the coastal parks or at higher elevations (if you've never ridden up in Big Bear, this is a great time to do it!).
3) Pack extra water. Consider a bladder and bottles, depending on ride length, on hotter days. It's always better to have more water than not enough!
4) Use larger or insulated bottles. You can freeze one the night before, or both if you're also carrying a hydration bladder. If you wear a cycling jersey with rear pockets, putting a frozen bottle in the center pocket will help keep you cool.
5) Use a hip pack instead of a full-sized hydration pack. Getting extra material off your back keeps your cooler!
6) Carry electrolytes. Replace essential salts lost through perspiration with electrolyte tabs (Nuun or other) in one of your bottles (avoid putting these in your hydration bladder, it only invites mold and bacteria growth!).
7) Wear lighter, cooler clothing. Avoid heavy fabrics and dark colors on hot days. Dakine, Patagonia, Troy Lee, Fox and other brands are using lighter materials with vents and other features to help you stay cool.
8) Eat...even if you don't feel like it. You may lose your appetite in the heat, but the last thing you want to do is bonk on a hot day. Keep your energy and blood sugar up by fueling before you feel hungry; consider gels or liquid fuel (like Gu Roctane mix) that are easy to digest on hot days.
9) Watch for signs of heat stroke and/or exhaustion. According to the CDC, symptoms include a high body temperature above 103 degrees, red/hot/dry skin without any sweating, rapid pulse, throbbing headache, dizziness, nausea or confusion.
10) Pace yourself on climbs and rest often. Take it easy on longer climbs, and let your body recover, ideally in the shade. Heat stresses your system, so it can be easier to overdo it on hot days.
Also, don't forget about sun protection: glasses, sunscreen and gloves are a must!