Weather in Colombo in December

Shoulder season. December sits in between. You will get good days and you will lose some. You should expect rain on 21 days of the month, which is more days wet than dry.

December ranks 8 of 12 in Colombo: past the worst of the year but short of January, which is the month to book if the dates are open.

Rain on 21 of the month's 31 days, 6 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 84% nothing dries, including you.

What the averages hide

Averages flatten a month, and this one hides a few things: 6 days top 30 °C — hot spells arrive, but they break; the day barely swings — 5.2 °C between the overnight low and the afternoon high. Across the twenty years measured, the hottest December day reached 32.2 °C and the coldest night fell to 19.7 °C, and the wettest single day dropped 81 mm — roughly 46% of the month's rain in one day.

December is moderately variable: 25 mm in the driest year against 383 mm in the wettest, around an average of 175 mm. Roughly two Decembers in three land near that average, and the third does something else entirely.

Wind is light at 11.7 km/h, so the temperature on the page is close to the temperature on your skin, and humidity runs at 84%, high enough to notice on the warm days without dominating them.

How December sits in the year

Temperatures hold steady either side: 29.2 °C in November, 29.2 here, 29.8 in January. Nothing about the timing within the month matters much. Rain is the thing that moves: January brings 9 days less of it, so pushing the dates later buys drier weather.

Daylight in December

Colombo sits close enough to the equator that daylight barely moves all year — 11.7 hours in December, 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 28.3 °C in December — warm enough that the water offers no relief from the heat. The sea peaks at 29.9 °C in April and bottoms out at 27.2 °C — water lags the air by a month or two, which is why the best swimming often comes after the best weather.

How busy it gets

Shoulder. The value months — prices ease off and you get the place closer to itself.

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

December in Colombo versus nearby

If Colombo is one option among several, the nearby comparison is worth making. Kandy is a better bet in December — 3.3 °C cooler, 1 day less rain. Trincomalee is a better bet in December — within a degree on temperature, 1 day less rain.

So: December works, with January the better month by 14 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 December.