Bulgaria's weather agency has issued a yellow warning for frost in 24 regions.
The warning covers all of Vidin, Lovech, Pernik, Kyustendil, Sofia region, Sofia city, Pazardzhik, Plovdiv, Smolyan, Kardzhali, Haskovo, Stara Zagora, Gabrovo, Sliven and Yambol. It also covers parts of Montana, Blagoevgrad, Vratsa, Pleven, Veliko Tarnovo, Dobrich, Targovishte, Razgrad and Shumen.
The day will be mostly sunny, though clouds will build up for a while in the eastern half of the country. Winds will stay light.
Highs will range from 21 to 26 degrees Celsius, with 23 degrees expected in Sofia.