When to run?

This is a difficult one...should I run early in the morning or late in the evening on Sunday?

If I can believe the forecasts it is going to be 13 C at 0700hrs rising 23 C by 1300 hrs, about 1-2 C per hour so by the end of my run tomorrow it could be about 18 C.

However I could wait to the early evening and run as the sun sets when it is cooler, either way it is going to be hot...yuck