Torrential rain fell across Senegal on Wednesday, causing floods in the capital Dakar and bringing down a section of one of the main highways into the city.

Cars, scooters and pedestrians inched through torrents of brown knee-deep water as unusually strong downpours battered the semi-arid city, where sandy roads and flat-roofed houses are poorly equipped for the July to October rainy season.

"Every year... we have difficulty moving and getting home, it's a real problem," said stranded resident Mohamed Ly.

Pedestrians piled onto horse-drawn carts normally used for goods and construction materials to cross particularly deep puddles.

"We pay 200 CFA francs ($0.3145) for a crossing. It's expensive for a distance we would do on foot," said Ly, taking a seat among other passengers.

A group of children waded past, the smallest on piggy-back.

Rain typically falls in intense bursts during Senegal's rainy season. Showers last a few hours and are separated by several days of dry weather.

Wednesday's downpour was particularly strong, however, with 84 millimetres (3.3 inches) of rain recorded in Dakar in the space of two hours, according to the national civil aviation and meteorological agency (ANACIM).

Rainfall qualifies as "extreme" when it surpasses 50 millimetres, said senior ANACIM official Pape Ngor Ndiaye.

"Every year it seems to be getting worse," said Ndeye Ndiaye. "It is the first time I am seeing this."

Other grumbling Dakar residents noted flooding was a recurring problem in the ocean-facing city. Many blamed the lack of drainage systems and other infrastructure.

"Every year, we face the same situation," said Mor Kane. "We need a government that solves problems."