It'll surely be better than last year. It wasn't the brightest idea to place the Spa 1000 KMs into April, clever mind that was planning that... However, May is another chapter in the Ardennes and I have often found years with splendid sunshine and fair temperatures in May. There's the season opener of the Belcar series (Belgian GT) at Spa this weekend. I might have a drive and look.
BTW, they seem to have the same weather in Instabul this weekend as at Spa last year during the 1000k weekend. It was chilly this week at Istanbul as some early arriver from Rollcentre said and it will be raining this weekend. This is what weather.com told me. I think I stay here over the weekend.