Diani Beach (Diani) weather in September

September in Diani Beach: hot, a little rain, with clean air — fine if you can take 19 rainy days.

Updated September 2026 · climate normals from ERA5 reanalysis

Diani Beach🇰🇪 Kenya · Swahili Coast · Beach89
  1. 91Jan
  2. 91Feb
  3. 87Mar
  4. 72Apr
  5. 71May
  6. 84Jun
  7. 88Jul
  8. 89Aug
  9. 89Sep
  10. 85Oct
  11. 85Nov
  12. 87Dec

#4 of 12 months in Diani Beach · #262 of 1413 destinations to visit in September · comfort 89/100 (tier A)

Days
28°C
Nights
23°C
Wet days
19
Sun
10.9 h
Humidity
79%
Daylight
12 h
Diani Beach, Kenya
Photo: imsogabriel Stock · Pexels

Traveller notes on Diani Beach in September

Notes from nearby Mombasa (26 km away)

Diani Beach doesn't have its own notes for September yet — these are about Mombasa, close enough to share the season.

September here is described as fine weather with the occasional short shower, and notably not as hot as the rest of the year. Our rain figures say exactly that, in a way either number alone would hide: 44.8mm spread across 15.2 days is about three millimetres on each day it rains - frequent, brief, and not a reason to change a plan. Air is 28.7C but reads as 32C at 77.4 percent humidity, and the nights hold 22.6C. The sea is 26.6C. The caveat regulars add is about conditions rather than weather: it is windy now, 18.4 kph, so the water turns choppy and visibility drops - a better month for the beach than for diving. The record: 10.8 hours of sun and AQI 35.
ShortShowersChoppyWater · September · 1 month ago · about Mombasa · Read more on Tripadvisor ↗

Other months in Diani Beach

Diani Beach's forum is split on July: some posters call this some of the coast's best weather, with days in the high 20s C and nights around 22C, while others describe a genuinely messier stretch of mostly cloudy skies and sharp showers with just a couple of sunny hours to work with. Humidity stays high regardless of which pattern you get. The consistent good news is the sea clears up for snorkeling and diving by July, and several posters noted Kenya's weather has gotten less predictable year to year, so it's worth going in with flexible expectations either way.
KenyaSouthCoastRegular · July · 1 month ago · Read more on Tripadvisor ↗
Forum posters name January and February as the hottest months here, but also the driest - averaging around 5 rainy days a month, the lowest rainfall stretch of the year by posters' count. Sea temperatures in January are reported around 27-28C, genuinely warm for swimming, though posters flag a practical local quirk: low tide (timing varies day to day, sometimes morning, sometimes afternoon) can pull the water back far enough to make swimming impractical for a stretch of any given day regardless of season. Posters generally rate the whole year as good here except for the wetter May-June stretch and a possible rainy patch around September-October, positioning January squarely within the best overall window.
Tripadvisor community · January · 1 month ago · Read more on Tripadvisor ↗

Add your own note from Diani Beach's card on the map.

Diani Beach climate normals — September

Daytime high28°C / 83°F🥵 hot
Nighttime low23°C / 73°F
Feels like (high)31°C / 88°F
Sea temperature26°C / 80°F😎 warm sea
Rainfall60 mm / 2.4 in🌦 some rain
Rainy days19 days
Humidity79%💦 very humid
Dew point21°C / 71°F
Sunshine10.9 h/day
Daylight12.1 h
Wind19 km/h / 12 mph
Air quality (US AQI)36🍃 good

Monthly averages from ERA5 reanalysis. AQI is the mean US Air Quality Index for the month.

Crowds in Diani Beach in September

How busy the place itself is — school and mass holidays, the months an editor tagged, and how sought-after the weather makes them. Never part of the comfort score.

Shoulder seasonschool holidays in 2 of the markets that fill it, an ordinary month(estimated)

JFMAMJJASOND

Peak crowdsBusyShoulder seasonQuiet

Best months for Diani Beach's weather

Ranked by this destination's own climate comfort score across the year — a different thing from how busy it gets (see Crowds above).

Fair weatherDiani Beach's best weather comes in January, February and August — separate windows, not one continuous season.

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Best weatherFair weatherToughest weather

What's on in Diani Beach in September

Recurring seasonal events, natural spectacles, closures and holidays — curated and sourced.

  • Season

    Kusi wind season

    15 Jun – 20 Sep · usually

    The south-easterly blows hard and steady, which suits kites and does not suit lying still on the sand. It also pushes seagrass wrack onto the beach, and the hotels rake it off every morning. Source ↗

  • Nature

    Humpback whales offshore

    1 Jul – 30 Sep · usuallyWhale season

    Humpbacks pass the reef edge on their way north through the middle of the year and are close enough that some sightings come from the beach. Boats go out from Diani when the sea state allows it. Source ↗

What's on around the world in September →

Nearby, and something's on

Within 300 km of Diani Beach — a day trip or a short hop — with something on this month. Never part of the comfort score.

Where is Diani Beach?

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Diani Beach in September — FAQ

Is September a good time to visit Diani Beach?
September in Diani Beach: hot, a little rain, with clean air — fine if you can take 19 rainy days. It ranks #4 of 12 months for Diani Beach on SeasonMap's comfort score (89/100).
What is the weather like in Diani Beach in September?
In September, Diani Beach averages a daily high of 28.1°C and a low of 22.8°C, with about 60 mm of rain over roughly 18.8 rainy days.
What is the air quality in Diani Beach in September?
Diani Beach has a mean US Air Quality Index of about 36 in September.

Within 300 km: Lamu's Maulidi around 15 Jul – 30 Sep, and Mombasa's Kusi, the cool monsoon around 15 Jun – 30 Sep.