I didn't sleep very well last night, and when I finally got back to sleep I slept in until 8 am and got about 6 1/2 hours of sleep. Getting up late meant that I left for my run late and ended up running in the hottest part of the day :( When I got back from my 13 mile long run, the shade temperature under my deck was 103 (F). My wakeup HR was 48, though, and I felt good during the run.
I felt fine and handled the heat well until mile 10, and then I started to lose energy. I had drunk most of my 20 ounces of water and 20 ounces of Gatorade, and I walked much of that mile. I knew I was having problems when I got tired while running downhill and had to walk at the bottom of the hill.
When I got to the bottom of the hill, I saw a big guy spraying down his driveway, and I asked him if he would spray me too. He said, "Sure!" Boy, that water felt good! He had a big hose, and I was soaked to the skin, from head to toe. After that I felt great and ran the next mile faster than I had run any mile that morning. At the end of the mile, I started to heat up again, but by then I was going past a picnic area that had a water fountain. I stopped at the fountain, took several big drinks and poured a lot of water on me. I filled my water bottle half full and continued my fast pace 1.5 miles to the end of the run. I even increased my pace with a little kick during the last 200 feet or so of the run.
I completed the 13-miler in 2:56, which is a good time for me, considering that I walked over half of mile 10 and stopped twice to put water on me. That was a good time considering the high temperature I was in. The 103 (F) was a shade temperature. Most of my running was in direct sun with only spots of shade here and there, and the direct-sun temperature was probably 125 or more (F). By the time I got home, the sun had moved past my kitchen window, and I couldn't measure the temperature of the direct sun. But, a 25-30 (F) difference between the shade and direct-sun temperatures has been common.
On these hot days, I'm going to take a 3rd bottle with me (two of water and one of Gatorade). That will give me 60 ounces of liquid. I will also make use of that water fountain in the picnic area.