Colombo records about 2398mm of rain across roughly 119 wet days a year, which is a 33% chance on an average day. May is the wettest month at 371mm (15% of the annual total) and February the driest at 59mm. Local rain type: monsoon. Colombo has two monsoon seasons — expect rain in any month but especially April-June and October-November. Afternoon showers are warm and brief.
Chance of rain on an average day: 33%
Rainfall climatology for Colombo. The live hour-by-hour answer for today loads at the top of this page from Open-Meteo and refreshes through the day — the figures below describe a typical year, not today.
Last updated: · Live forecast data refreshes hourly.
| Annual rainfall | 2398mm |
| Rain days per year | 119 |
| Odds on an average day | 33% |
| Wettest month | May — 371mm over 20 days |
| Driest month | February — 59mm over 3 days |
| Rain type | monsoon |
| Best dry window | January through March offers the driest conditions. |
| Worst rain window | October and November bring the heaviest inter-monsoon rainfall. |
May delivers 529% more rain than February (371mm vs 59mm). That gap is the difference between planning around showers and ignoring them.
No single month holds more than 15% of the annual total, so rain in Colombo is spread through the year — there is no season you can rely on being dry.
Colombo rain arrives in short, heavy bursts — shelter and timing matter more than gear.
Rain falls on about 20 days in May against 3 in February — the frequency swing matters more for planning than the millimetre totals.
Climate normals. Use them to judge whether today's live forecast at the top of the page is typical or unusual for the season.
| Month | Rainfall | Rain days | Chance on a given day | Highs |
|---|---|---|---|---|
| January | 62mm | 3 | 10% | 30°C |
| February | 59mm | 3 | 10% | 30°C |
| March | 105mm | 6 | 20% | 30°C |
| April | 225mm | 12 | 40% | 31°C |
| May | 371mm | 20 | 67% | 31°C |
| June | 179mm | 10 | 33% | 32°C |
| July | 118mm | 6 | 20% | 32°C |
| August | 105mm | 6 | 20% | 32°C |
| September | 173mm | 9 | 30% | 32°C |
| October | 348mm | 19 | 63% | 31°C |
| November | 315mm | 17 | 57% | 31°C |
| December | 170mm | 9 | 30% | 30°C |
Rain probability is the chance that at least 0.2mm falls at your location — not how long it rains. For Colombo we combine the hourly probability curve, expected volume in millimetres, and the city's own rainfall record into a single umbrella verdict.
| Factor | Weight | What it measures |
|---|---|---|
| Hourly probability | 40% | Peak and sustained chance of measurable rain across the next 24 hours. |
| Expected volume | 30% | Total millimetres, which separates a passing shower from a genuine soaking. |
| Timing & duration | 20% | When rain starts, when it eases, and the longest continuous dry window. |
| Local rain type | 10% | Drizzle, brief showers, thunderstorms or monsoon — each needs different gear. |
Live hourly values come from Open-Meteo and refresh through the day. Monthly rainfall figures are climate normals, so they describe a typical year rather than a forecast.
Colombo records rain on roughly 119 days a year — about a 33% chance on any given day — totalling around 2398mm.
May, with about 371mm over 20 rain days. That is 15% of the entire year's rainfall in a single month.
February is the driest month at 59mm across roughly 3 days. January through March offers the driest conditions.
Colombo has two monsoon seasons — expect rain in any month but especially April-June and October-November. Afternoon showers are warm and brief.
No. Probability is the chance that at least 0.2mm of rain falls at your location at some point in the period. Check the expected millimetres alongside it: 40% with 0.4mm is a passing shower, 40% with 12mm is a soaking.