On Wednesday, a downpour caused major traffic jams on most of Tehran's streets and a first rainfall earlier in December followed months without rain in the Iranian capital.

Iran's already arid climate has been hit by its worst drought in over 60 years, with rainfall in Tehran at low levels not seen for a century, authorities said in October.

The first autumn rains are usually expected in September.

Amir Abkari, a bus driver on a route serving Tajrish Square in northern Tehran, said he was delighted by the rain.

"We thank God for the rain we've had over the last few days. The air is cleaner, and even though the traffic is heavier, we can cope with it," the 58-year-old said after dropping off his passengers.

Abkari explained that he and his neighbours had recently made efforts to reduce their water consumption in line with calls from authorities.

With the rains came a dusting of snow on the mountains north of the capital, visible after a months-long absence.

Armaghan Kamyabi, a 35-year-old jeweller, said he was "happy that it has rained. I hope the rainfall will continue and that we will soon see snow" in Tehran.

Despite the rain, a water sector official told Iran's ISNA news agency on Tuesday "the expected rains still do not compensate for the water shortage in the country's dams" and that "reservoirs remain at a minimum level".

To save water, the government announced in November that there would be periodic night-time cuts.

Tehran, located on the southern slopes of the Alborz Mountains, experiences hot, dry summers, sometimes rainy autumns and winters that can be harsh and snowy.

Iranian President Massoud Pezeshkian has warned several times that Tehran, a city of more than 10 million people, may have to be evacuated due to lack of rain, without specifying how such a large-scale operation would be carried out.

On Thursday, Iran's Mehr news agency reported heavy rains had caused flooding, particularly in the provinces of Zanjan and Kurdistan in the west of the country.

The country's meteorological organisation is forecasting rain and snow in western and north-western Iran from Saturday.

Authorities said on Wednesday that they had carried out cloud seeding operations in certain regions of the country.