The only chance I rain that I can see at this moment is on Wednesday, and even that looks very marginal. A cold front will be approaching during the day, and crossing Daytona at night, so what little rain may come with this front could be mostly on Wednesday night. There will be a couple practice sessions that day, but I don't expect that there will be enough rain to have any impact - just a few sprinkles or light showers.
Behind the cold front on Thursday, the weather will get quite a bit colder, with breezy and gusty winds. Gusts of 25 to 30 mph can be expected at times. North winds at 10-15 mph will continue into Friday, which will keep temperatures cool, but at least it will be sunny all day.
On Saturday, high pressure will move off the east coast, shifting winds to a more southerly direction, which will help warm temperatures into the 70s for the start of the race. An upper level low pressure trough will approach on Sunday, but any rain with it is expected to hold off until Monday. It will result in some increasing clouds on Sunday afternoon, but temperatures should still be able to rise into the mid 70s by the end of the race.
I plan to have the next forecast update posted on Wednesday, unless there's a major change in the forecast.