With temperatures reaching record levels, riding in this extreme heat is a serious thing. Old school riders will shrug it off and say that it's part of cycling, but you can dehydrate yourself and suffer from heatstroke if you're not careful. That's not fun at all.
I'm not saying that you should stay indoors and wait for the wet season. Just use your coconut shell (a.k.a. common sense) and ride intelligently.
Here are some of my tips to enjoy biking without the risk of injuring yourself:
1. Hydrate, hydrate, hydrate. Drink lots of liquids more often. In case you didn't notice, those are two factors: volume (amount of liquid that you take) and frequency (how often you drink). A common rule is you should finish a water bottle every hour. In this extreme weather, I believe bringing a hydration pack is a must. I'd go for the extra weight and having all the liquid you need with you rather than getting thirsty in middle of the trail with no sari-sari store in sight.
2. Wear Sunblock. Excessive exposure to the sun will damage your skin. I usually apply sunblock an hour before the ride. It doesn't stop there -- you would need to reapply this every few hours because of your sweat. I usually go for the higher SPFs, but there are new studies saying that it's a myth. It's really up to you. What's important is that your skin is protected. Some wear arm warmers instead of putting on sunblock. Personally, I don't recommend it because they're exactly that - arm warmers, which is opposite of what you want to happen.
3. Avoid exposure to the extreme heat. Checking Accuweather, the temperature is at its peak between the hours of 11 a.m. to 4:00 p.m. With this information, schedule your rides early in the morning and so you can finish early. If you choose to ride in the afternoon, don't forget to bring blinkers and headlights, in case you run out of daylight.
4. Wear dark-tinted eyewear. You need to protect your eyes. Black-tinted lenses are ideal. Try to avoid clear and yellow-tinted lenses, as those are for low-light conditions.
5. Wear a properly vented helmet with a visor. Those nice skateboard-inspired helmets may look cool, but with very little vents to allow heat to escape, they're more like brain ovens. As for visors, they do a great job at blocking the sun.
6. Wear light colored clothing. Dark colored ones absorb heat.
Do you have your own tips at riding in this weather? Feel free to share them at the comments section. :)