After a dry, warm start to October, the weather in Bulgaria will be cool, wet and windy until the end of the month, said Anastasia Stoycheva, a forecaster at the National Institute of Meteorology and Hydrology (NIMH). Most rain will fall in the east and especially the south-east, where 50 to 75 litres per square metre could fall in 24 hours in places.

Part of eastern Bulgaria is under an orange code warning for heavy rain.

"We will see the other face of October. So far it has been pleasant, now it is turning truly autumnal," Stoycheva told BNT.

The first days of October had almost no rain, and much of northern and western Bulgaria was warmer than normal. Stoycheva said the rain is welcome because it has been quite dry so far.

Some parts of western Bulgaria have already had 15-20 litres per square metre. In the coming days the rain will spread to the rest of the country. Up to about 25 litres per square metre is expected in places in the west and up to 40 in the south and east.

The weather comes from a trough of low pressure high above the Balkans, which will form low-pressure systems near the ground. They will move across the southern part of the peninsula, and how much rain each area gets depends on their path. Cold air will follow the cyclone from the north and north-east, so the rain will come with a drop in temperatures and stronger wind.

It will rain in the coming days, with short clear spells. Thursday will be dry, with more sun and a brief warm-up. A new weather system will bring rain on Friday, and it may last into part of Saturday. The weather will slowly improve over the weekend.

Between 19 and 26 October, new systems will bring more rain, heaviest in the eastern half of the country and mostly in the south-east. Stoycheva said the rainfall map will look quite different by the end of the month.

"First we will get the moisture we need, and then we will have to think about the fact that rainfall is well above the norm," the forecaster said.

Thunderstorms are still possible, mainly in eastern and south-eastern Bulgaria, where it is relatively warmer. Stoycheva said they will not be as strong as in summer. More moisture will also bring fog, which cuts visibility and makes driving harder, especially early in the morning. The forecaster advised drivers to take care because of the wet roads, fog and earlier dusk.

Most of the rest of October will be colder. Daytime temperatures will mostly be between 11 and 16 degrees, and both lows and highs will be about 1-2 degrees below normal. Very low minimum temperatures are not expected, but the weather will feel clearly worse than at the start of the month.

Average daily temperatures will be close to the norm and will drop below it, so autumn will be felt more, Stoycheva explained. She said the warmth at the start of October was a so-called Indian summer, and summer heat will not return.

Western Europe will be warmer because of areas of high pressure.

In Sofia, one of the conditions for switching on the heating is three days in a row with an average daily temperature below 12 degrees and a forecast of lasting cold.