Weather in Colombo in May

A hard month. May is a hard month in Colombo, and worth planning around. You should expect rain on 26 days of the month, which is more days wet than dry.

May ranks 11 of 12 — near the bottom of Colombo's year. January is the month that works, and the swing between the two is 19 points, which is a different holiday rather than a slightly better one.

Rain on 26 of the month's 31 days, 8 of them heavy. At that frequency a wet-weather backup is not a contingency, it is the itinerary — book the indoor things first and treat the clear days as the bonus. Natural fibres and a second shirt for the day. At 86% nothing dries, including you.

What the averages hide

Averages flatten a month, and this one hides a few things: 12 days top 30 °C — hot spells arrive, but they break; the day barely swings — 3.1 °C between the overnight low and the afternoon high. Across the twenty years measured, the hottest May day reached 32.8 °C and the coldest night fell to 24.5 °C, and the wettest single day dropped 104 mm — roughly 47% of the month's rain in one day.

May is moderately variable: 79 mm in the driest year against 530 mm in the wettest, around an average of 223 mm. Roughly two Mays in three land near that average, and the third does something else entirely.

Wind is light at 14.2 km/h, so the temperature on the page is close to the temperature on your skin, and humidity at 86% is the real story though — it is the number that decides how the day feels, not the 29.8 °C.

How May sits in the year

Temperatures hold steady either side: 30.9 °C in April, 29.8 here, 29 in June. Nothing about the timing within the month matters much.

Daylight in May

Colombo sits close enough to the equator that daylight barely moves all year — 12.4 hours in May, against a range of just 0.8 hours across the whole calendar. Sunrise and sunset land at roughly the same time whenever you come.

Sea temperature

The sea sits at about 29.3 °C in May — warm enough that the water offers no relief from the heat. This is the warmest the water gets all year.

How busy it gets

Off season. The genuine off season: cheapest by a distance, with the caveat that some tours and restaurants close entirely.

Crowd levels are estimated from climate desirability and school-holiday calendars, not from visitor numbers.

May in Colombo versus nearby

If Colombo is one option among several, the nearby comparison is worth making. Kandy is close enough to be a coin toss — within a degree on temperature, 8 days less rain. Trincomalee is close enough to be a coin toss — 2.4 °C warmer, 15 days less rain.

So: May works, with January the better month by 18 points if the dates can move. If they cannot, nothing here should stop you booking.

Every month in Colombo

See all twelve months in Colombo, or where else to go in May.