The summer is fast approaching and with the summer comes the heat! The good news is that the body can acclimate to the heat but in general it takes two weeks of training under these conditions. A few good tips to know are that the mornings are the coolest time of day to run, but are also the most humid. The evening is the least humid, but it’s hotter than the morning. I personally struggle to run in the morning, thus on those incredible hot summer days, I generally start my run around 8pm.

I’ve found that a lot of runners do not adapt to a hot race day. It’s important to realize that when it’s hot you need to adjust your strategy accordingly. The ideal racing temperature is right around 50 degrees. I went ahead and put in a 3:00 hour marathon at 50 degrees using the Jack Daniels Calculator to give you an idea as to how much the heat will slow you down.

Temperature Time
60F/16C or below 3:00.0
65F/18C 3:01.2
70F/21C 3:02.4
75F/24C 3:03.8
80F/27C 3:05.3
85F/29C 3:06.9
90F/32C 3:08.7
95F/35C 3:10.5

There are also a lot of other individual variables. The taller/bigger the runner the more negatively impacted they will be due to the heat as they have a larger surface area. Also slower runners will be impacted by the heat even more, especially in a long race such as the marathon as the temperature increases through out the morning.

Thus, when you’re lacing up your shoes for the local fourth of July road race, realize that the odds of you setting a PR are slim to none.