Conversely, as you head inland from the coast, the temperatures will usually increase significantly. When it's 70 degrees on the the Los Angeles coast during the summert, it can be 90 to 100 degrees Fahrenheit just 20 to 30 miles inland towards the mountains.
Because of the Pacific Upwelling, those who live near the San Francisco Bay Area have lots of fog in the summer. This prompted Mark Twain years ago to remark, "the coldest winter I ever spent was a summer in San Francisco." While that can lead to some chilly riding in normal weather conditions, the fog can be a godsend if it's hot. Unfortunately, the fog along the northern California coast usually burns off by mid-day, so plan accordingly.
More: Cycling Hydration Myths
Head to the Shade
I have a number of cycling routes that have lots of tree-lined roads. The shade of the trees can provide significant protection and some much-needed cooling during heat waves. For the spring and fall I do the opposite. I have plenty of planned routes that are exposed to the sun where it's warmer and dries out quicker after a rain.
Be Aware of Signs for Heat Stress
There is also cooling that occurs when you are riding down the road because of the evaporative cooling of your sweat. If you stop getting that cooling effect, it is a good indication that you are in danger of heat-related stress such as heat stroke.
You should also be aware of frequent stops on busy roads. When you're stopped at a red light, the sun-baking rays can be totally debilitating. For this reason, when I ride in the heat I try to use roads which don't have a lot of stoplights. Even though it's hot, you still must obey the rules of the road. Trying to sneak through a red light because it's hot just adds another element of danger that no one needs.
In Part 2 of this article I will discuss more ways to beat the heat.
More: Thermoregulation and How it Affects Your Cycling
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