But motorists in South Ayrshire still faced flood chaos as major roads remained closed, and racegoers were advised to leave extra time for their journey to the meeting at Ayr.
The Scottish Environmental Protection Agency issued a flood warning for Ayrshire and Arran last night, while hundreds of drivers faced lengthy delays. The Bellfield Interchange on the A77 was worst affected, while police today said just one lane was open on both carriageways of that road. The A76 around Cumnock was still closed, as was the A71 at Galston.
Four flights were diverted last night, when passengers on Ryanair flights from Palma, Malta and Malaga landed in Glasgow. Holidaymakers jetting in from Poland were switched to Edinburgh.
The airport re-opened at 6am after runways had been cleared of water but it was another two hours before the first flight took off.
An airport spokesman said: "Passengers flying from the airport today should check-in as normal.
"However, early flights will experience some delays as aircraft are re-positioned."
Chief executive Iain Cochrane said: "We've never experienced this level of rainfall in such a short period of time. The burn that runs under the main runway burst its banks."
The race meeting at Ayr, which was abandoned yesterday, was to go ahead as normal today, with the Duke and Duchess of Rothesay to present a trophy.