Race day weather can be very unpredictable. Use your long runs as practice for a potentially hot marathon day. If we have an especially warm or humid day, be sure to do your scheduled run. Do not avoid your run, thinking that the October race day will be cool. Hot October weather is very possible (and it has happened in recent years!), so you need to train in the heat and humidity. However, if the relative humidity and temperature meet in the extreme danger section of the above chart, it is wise to train indoors. After all, the race would be cancelled under those conditions anyway.
Keep your head up during these upcoming long runs in the hotter temps, even if the heat and humidity make your runs tougher than they have been thus far. Think about how far you have come, especially if this is your first marathon training experience. Even if you have to slow down your pace, don’t worry. Just remember all of the things you have already accomplished and the major milestone you are training to achieve. Remember all the people and causes you are raising money for, and do not forget all of the family and friends cheering you on and donating money to your fundraising pages.
Also, remember that it is ok to slow down on hot, humid days. Pace yourself by listening to your body. I always preach the conversational pace for long runs (i.e. you should be able to carry on a conversation while running), and the long, hot run is no exception. However, your pace may be even slower than usual, so be sure to make yourself feel comfortable with that even before you head out for your run. Your long runs will, on their own, be chances for you to slow down a bit from your shorter distance pace, but on a hot day, you will have to slow down even more. This will mean more time on your feet. Think of it this way, the longer you are on your feet, the more you are building your endurance. The slower, longer effort you put in during a very hot long run is definitely helping you, even if you do not feel full of energy at the end of it.
Hot, humid days usually lead to humbling training runs. However, know that you are teaching your body to push while under difficult conditions. You are going to feel super strong if your race day turns out to be any less difficult than your hot training runs.