We raced the 50K World Champs in Doha around 6pm (finished after 9pm). The year before they had the 100K World Champs in Doha around 6pm (finished after midnight). This was in Dec. with temps around 80 degrees, high humidity, and wind. They had enough lighting on the course that we could see well. I spent the months leading up to it by doing my short run at midday with layers on and longer runs/workouts in the evenings usually wearing extra layers. Not having the radiant heat in Doha was a huge help! The sun was hot during the day. Summer in Doha will be grueling but better without the radiant heat. Do we know what the course is like? We did 5K loops around the Aspire Zone area-- going from smooth road, cobblestones, and jumping on sidewalks of slick/dusty marbling. Drug testing takes a good 2-3 hrs afterwards.