Residents in more than 40 counties have been told to brace for heavy downpours, flash floods and strong winds this week. The Kenya Meteorological Department (KMD) says the wettest days of the current spell fall between Monday, October 26 and Wednesday, October 28.

In an updated advisory issued on Sunday, the department said moderate to heavy rain of more than 20 millimetres in 24 hours is expected over much of the Coast, North Eastern Kenya, the highlands east and west of the Rift Valley, the Central Highlands, parts of Nairobi and sections of the South Eastern Lowlands. Rainfall is expected to ease gradually towards Friday, October 30.

Counties on the list

According to Capital FM's report of the Sunday advisory, the counties at the Coast are Kwale, Mombasa, Kilifi, Tana River and Lamu. In the north and north east, Garissa, Wajir, Mandera, Marsabit and Isiolo are named.

In western Kenya and the Lake region, the list covers Migori, Nyamira, Kisii, Kisumu, Siaya, Homa Bay, Bungoma, Busia, Kakamega and Vihiga. In the Rift Valley it covers West Pokot, Baringo, Elgeyo Marakwet, Trans Nzoia, Nandi, Uasin Gishu, Nakuru, Kericho, Bomet, Narok and Kajiado.

In the central and Mount Kenya region, heavy rain is expected in Kiambu, Murang'a, Kirinyaga, Nyeri, Nyandarua, Laikipia, Embu, Meru and Tharaka-Nithi. Parts of Nairobi, Machakos, Makueni, Kitui and Taita Taveta could also be affected.

Outlets have reported slightly different totals for the number of counties, but the regions named in the department's advisories are the same.

Floods where it has not rained

The department warned that flash floods could hit places that have not seen intense rainfall, because runoff from higher ground can sweep through areas downstream. In its earlier advisory on Friday, it said residents in all the areas mentioned should "remain vigilant for potential flash floods and poor visibility".

Strong southerly to south-easterly winds of more than 25 knots, about 46 kilometres per hour, are forecast over the coastal, eastern and northern regions. The department had also warned that ocean waves could rise above two metres and asked fishermen, boat operators and others at sea to take care.

Flash floods could occur even in locations that have not experienced intense rainfall, the Kenya Meteorological Department warned.

What residents are being asked to do

KMD urged the public to keep checking weather updates and not to cross flooded roads, rivers or streams, whether on foot or by car. Motorists were told to drive carefully because heavy rain and poor visibility make roads more dangerous. The warning comes as holiday travel on the roads picks up.

During thunderstorms, residents should shelter inside safe buildings rather than under trees or near metal-grilled windows, which can attract lightning. In areas expecting strong winds, households were asked to secure loose items such as iron sheets.

A wetter-than-normal season

The warning is in line with KMD's outlook for the October to December short rains. That outlook forecast above-average rainfall over most of the country as El Nino conditions build. The department's October bulletin had also flagged above-normal rain for the Coast, the North East and parts of the central region, including Nairobi.

Nairobi has had mixed weather in recent days. Heavy showers have flooded some streets, while other days have been unusually hot. Forecasters say this kind of variability is common as the season sets in.

County disaster teams in flood-prone areas are likely to be on alert, especially along the Tana River and in low-lying parts of the Coast and the Lake Victoria basin. Authorities have in the past advised families living near riverbanks to move to higher ground when water levels rise quickly.

The department said it will keep monitoring the weather and issue updates if conditions change.

Photos: Capital FM (Nairobi CBD in the rain); Kenyans.co.ke (pedestrians in a flooded Nairobi street). File images.