A storm like Adam, under a different name, will reach Bulgaria on the night before Friday, climatologist Prof. Georgi Rachev has said.
He said the rain will be heavy, mostly in western Bulgaria. The most will fall on Thursday and Friday.
Adam brought record rainfall to Spain and is now over the French Riviera, where more than 100 litres per square metre are expected, and over 120 in places.
Before the storm, Bulgaria will be very warm. On Wednesday, temperatures across the Balkans will rise to 24C.
It will also be warm on election day, Sunday 25 October.
Prof. Rachev said forecasts of a warm winter continue to prove right. Central heating may only be switched on towards the end of the month.