Monday will be sunny, with daytime temperatures set to keep climbing, weather forecasters say.
Highs will range from 21°C to 26°C, with Sofia around 23°C. Mornings will be cold, dropping to minus 1°C in some low-lying areas, where frost is expected, while the Black Sea coast will see 14-15°C. Sofia's overnight low will be around 3°C.
Along the coast, it will also be sunny, though some areas will see low cloud or fog in the morning. Highs there will stay at 19-20°C, matching the sea temperature. Waves will be light, at 1-2 points.
In the afternoon, patchy high cloud will move into northern Bulgaria. In the mountains, it will be sunny, with highs of around 18°C at 1,200 metres and around 11°C at 2,000 metres.
Winds will be light to moderate from the north-northeast, picking up to moderate northeasterly along the coast before shifting east in the afternoon. In the mountains, light to moderate winds will blow from the north-northeast.
Tuesday will start with a cool morning and almost no wind. Lows will range from 5°C to 10°C, dipping lower in some low-lying areas, where frost is again possible in parts of western and central Bulgaria. Daytime highs will reach 20-25°C.
Temperatures will rise on Wednesday and Thursday, with light south-southeasterly winds. The days ahead will be mostly sunny, with occasional spells of high cloud.
Updated (05.10, 13:29): Sofia's low tomorrow will be around 1°C, not around 3°C as first reported, bnt news says. A yellow level-1 warning for frost now covers almost all of Bulgaria tomorrow morning, not just a few valleys in western and central Bulgaria. Rain is expected in western areas on Friday, and Saturday will be cloudy with rain in many places. Temperatures will climb on Wednesday and Thursday, with highs of 23-28°C on Thursday.
Updated (05.10, 20:34): Minimum temperatures tomorrow will be between 2°C and 7°C, not around 1°C as first reported, burgas24.bg says.