site.btaThe Weather on May 13

Lows ranging from 5C to 10C, around 7C in Sofia. Cloud cover will decrease in many places, with brief fog in some spots in the lowlands in the morning. Thunderclouds will form around midday and into the afternoon, with brief rain and thunderstorms expected mainly in southwestern Bulgaria, along the Balkan Range and the northeastern areas of the country. Rain is expected in the far northwest. Light to moderate northeasterly wind. Highs: 15C - 20C, around 16C in Sofia. 

The Black Sea coast: Mostly sunny. Increasing cloud cover in the afternoon, with rainfall in isolated places along the northern coast. Moderate northeasterly wind. Highs: 15C - 17C. Sea water temperature: 14C - 16C. 

Mountains: Mostly cloudy and rainy, with snowfalls at an altitude of over 2,000 metres. Thunderstorms expected. Light to moderate north-northeasterly wind, northwesterly at highest altitudes in the Rila and Pirin Mountains. Highs: around 9C at 1,200 metres and around 2C at 2,000 metres. 

Source: National Institute of Meteorology and Hydrology