Rainfall activity is increasing across parts of Kenya as the country moves toward the October–December (OND) short-rains season, with Kericho and Bomet experiencing rainfall this morning, September 17, 2026, according to the situation described. Current forecasts also point to further rainfall and thunderstorms in parts of the Rift Valley and western Kenya in the coming days. However, it is important to distinguish between the rainfall being experienced now and the formal onset of the full El Niño-enhanced OND season. Kenya Meteorological Department forecasts indicate that the 2026 short-rains season is expected to be wetter than normal in many areas, while the exact timing and intensity of the onset can vary considerably from county to county. 

Kericho and Bomet experience rainfall

Residents in Kericho and Bomet counties are among those experiencing the changing weather pattern. The two neighbouring counties are located in the highlands west of the Rift Valley, areas that are particularly responsive to seasonal changes in moisture and rainfall.

The current forecast for Kericho shows cloudy conditions developing into afternoon showers and thunderstorms, indicating that rainfall activity is expected to continue beyond the morning in some locations. The forecast also points to additional showers and thunderstorms over the following several days.

Bomet is similarly experiencing cloudy conditions, with showers expected in parts of the county, particularly during the afternoon. The forecast indicates that rainfall activity could become more pronounced later in the day.This means residents should not interpret a dry spell during part of the morning as an indication that rain will not occur later. In these highland areas, rainfall can develop rapidly during the afternoon as cloud cover increases and atmospheric conditions become more favourable.

The rainfall is also significant because Kericho and Bomet are among the counties identified by Kenya's meteorological authorities as likely to receive above-average rainfall during the October–December 2026 season. 

 *Is this already the El Niño onset?* 

The appearance of rainfall in Kericho and Bomet does not by itself mean that the entire country has entered the El Niño season.

The Kenya Meteorological Department's seasonal outlook indicates that the 2026 OND season is expected to bring above-average rainfall to 43 counties, including Kericho, Bomet, Nandi and Narok. The agency expects the rains to be fairly to well distributed in many areas, although rainfall amounts and timing will vary geographically. 

In western Kenya and parts of the Rift Valley, including Kericho, Bomet, Nandi and Narok, rainfall is expected to continue from September into January. This is earlier than the expected onset in several other parts of Kenya, where the main short rains are forecast to begin later in October. 

Consequently, the current rains in Kericho and Bomet can be viewed as part of an increasingly active rainfall pattern, but the full seasonal picture will develop over the coming weeks.

 *What is happening in Nandi County?* 

Nandi County is also on the rainfall watch list. The current forecast for Nandi shows clouds and sunshine at present, followed by an increased possibility of showers and thunderstorms later in the day.

The forecast indicates that rainfall activity could become particularly notable during the afternoon and evening. This suggests that residents should be prepared for changing weather conditions even if some parts of the county are dry in the morning.

Nandi is particularly important in the current weather discussion because it is among the counties expected to receive above-average rainfall during the 2026 OND season. Kenya Met has indicated that the rains in Nandi and other western and Rift Valley counties may continue from September into January. 

The rainfall pattern may not be uniform throughout Nandi. One part of the county can receive a substantial shower while another remains relatively dry. This is common with convective rainfall, particularly when thunderstorms develop in isolated locations.

For today, therefore, the available forecast points toward rain developing later rather than persistent rainfall throughout the morning.

 *What about Narok County?* 

The situation in Narok is somewhat different from Nandi and Kericho for today.

Current conditions in Narok are largely cloudy, but the available forecast does not indicate a strong likelihood of widespread rainfall during the remainder of September 17. The chance of precipitation remains relatively low through much of the day.

However, that does not mean Narok is escaping the wider wet-season outlook.

Narok is included among the counties expected to receive above-average rainfall during the October–December season. Kenya Met's seasonal outlook places Narok among areas where rainfall is expected to continue from September into January. 

The forecast suggests that the possibility of thunderstorms becomes more noticeable in Narok during the coming days, particularly around September 20–22. Therefore, while residents may not see significant rainfall today in every part of the county, the broader weather pattern remains favourable for increasing rainfall activity.Rainfall expected across the Rift Valley

The development in Kericho and Bomet comes as Kenya Met has already identified a large number of counties where rainfall is expected between September 15 and September 21.

The list includes Bomet, Kericho, Nandi and Narok, alongside Nakuru, Uasin Gishu, Trans Nzoia, Elgeyo-Marakwet, West Pokot and other counties. 

This is important because it demonstrates that the rainfall being witnessed in parts of the Rift Valley is not an isolated development.

The September 15–21 forecast indicates that rainfall will occur in different parts of the country at different times. Some locations could experience afternoon showers, while others may receive thunderstorms or remain cloudy without significant rainfall.

 *Why the 2026 El Niño season is important* 

Kenya is preparing for a potentially wetter-than-normal OND season. The 2026 forecast has been influenced by a strengthening El Niño event and changes in the Indian Ocean Dipole, both of which can influence rainfall patterns in East Africa.

The August seasonal outlook reported that the El Niño conditions over the central and eastern equatorial Pacific had strengthened considerably. Kenya Met consequently projected enhanced rainfall during the October–December season. 

The forecast is particularly significant for farmers. Rainfall arriving earlier in some areas could provide opportunities for land preparation and planting. However, excessive rainfall can also create challenges, including soil erosion, waterlogging, crop damage and flooding.

Farmers in Kericho, Bomet, Nandi and Narok

Farmers in the four counties should therefore pay close attention to short-term forecasts rather than relying only on the seasonal prediction.

For tea-growing areas of Kericho and parts of Nandi, increased rainfall can influence soil moisture and agricultural conditions. In Bomet and Narok, where farmers engage in crop and livestock production, rainfall can improve pasture and water availability but can also create problems if rainfall becomes intense.

Farmers should monitor official weather advisories before planting, applying fertiliser, spraying crops or undertaking other activities that depend on dry weather.

The Kenya Meteorological Department provides county-level forecasts specifically to help farmers, county governments and other stakeholders plan according to local weather conditions. 

 *Possible flooding concerns* 

The biggest concern surrounding an enhanced rainy season is not simply whether it will rain, but how heavily and continuously it will rain.

Kenya's preparedness measures have already focused on possible impacts of above-normal rainfall, including flooding, disease outbreaks and damage to infrastructure. 

For Kericho and Bomet, residents living near rivers, streams and drainage channels should therefore remain alert whenever heavy thunderstorms occur.

In Narok and Nandi, the same precaution applies, particularly in areas where roads can become muddy or impassable after intense rainfall.

Thunderstorms can also be accompanied by lightning, strong winds and locally heavy downpours. Residents should seek shelter indoors during severe thunderstorms and avoid standing under isolated trees or near exposed electrical infrastructure.

 *What residents should expect in the coming days* 

The overall picture as of Thursday, September 17, 2026, is that rainfall activity is becoming more evident across parts of western Kenya and the Rift Valley.

Kericho: Rainfall and thunderstorms are possible, particularly during the afternoon, with additional showers expected over subsequent days.

Bomet: The county is experiencing cloudy conditions with showers possible, especially later in the day, and additional rainfall is forecast at intervals over the coming days.

Nandi: Rainfall is more likely to develop later in the day, with thunderstorms possible during the afternoon and evening. The county is also among those expected to experience above-average OND rainfall.

Narok: Conditions are currently less favourable for significant rainfall today compared with Nandi, Kericho and Bomet, but the county remains within the wider forecast area for the enhanced OND rains, with thunderstorms possible on some upcoming days.

The bigger picture

The most important point is that the rains are arriving unevenly. A rainy morning in Kericho or Bomet should not be interpreted as meaning that every part of the Rift Valley is receiving the same amount of rainfall.

Kenya Met's latest seven-day forecast shows that rainfall is expected across 44 counties between September 15 and 21. 

The seasonal forecast goes further, indicating that the enhanced rains in western and Rift Valley counties could persist from September into January. 

Therefore, residents of Kericho, Bomet, Nandi and Narok should prepare for increasingly changeable weather, with sunny or cloudy periods potentially giving way to afternoon or evening showers and thunderstorms.

The current rainfall is a notable sign of increasing wet-weather activity, but the formal character of the 2026 El Niño-enhanced short-rains season will become clearer as September progresses into October. Forecasts can change, so residents should continue following updates from the Kenya Meteorological Department, particularly when planning travel, farming activities or preparations against flooding.