Port Louis month by month — at a glance
Hover each month for the summary. Click to pin it.
01 Seven hundred and eleven against four thousand
Key moments at a glance
15 mm over 3 days, 279 hours of sun and 28.8 °C highs.
17 mm in the whole month, with 240 hours of sun and nights at 19.4 °C.
160 mm over 10 days and 82 % humidity. The season's peak.
26.7 °C by day and 19.3 by night, with only 18 mm of rain.
The figure matters for a practical reason: in Mauritius, the island's general forecast does not describe what happens in the capital. The west coast, where Port Louis is, is the driest, with values around 900 millimetres; the east is around 1,500 and the central plateau multiplies that figure.
The consequence is that you can be crossing the island in a downpour and arrive in the city with the sky open. The scale of the territory helps: this is an island where distances are measured in tens of kilometres, not hundreds, and even so the rainfall gradient is one of the sharpest there is.
02 Why it rains on the other side
The air arrives loaded from the southeast, climbs the plateau, unloads, and comes down dry to the northwest. The capital is on the dry side.
The mechanism is textbook, which is why it works so regularly. The southeast trades reach the island loaded with moisture after crossing the Indian Ocean. Meeting the relief of the south and east, the air has to rise, expands, cools and releases its water. That is orographic precipitation.
By the time that air descends the northwestern flank it has already left most of its moisture up above. Port Louis is exactly there, at the foot of the Moka range, in the rain-shadow sector. The same wall of mountains that shelters its harbour from the wind also takes away its rain.
03 December to April: cyclones
Although it rains little in annual terms, the water that does fall is highly concentrated, and coincides with the part of the year when there is cyclone risk. The wet season runs from December to April: 85, 131, 160, 83 and 87 millimetres. Between those five months they account for 546 of the year's 711.
It is also the hotter, muggier half. In January, February and March the mean high sits at 31.5, 31.4 and 31.5 degrees, lows do not drop below 23.8 and relative humidity stays above 81 %. It is not extreme heat, but the humidity makes it hard going.
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Cyclone risk is worth taking seriously when planning, not because one is likely to catch you, but because a warning can bring the island to a halt for a day or two. It is a factor that appears in no millimetre column and that can upend a short trip entirely.
04 Which month to pick
The good window is long and very clear: May to November. In those seven months rainfall runs from 48 millimetres in May to 15 in October, with only three to six rain days a month, and sunshine stays between 210 and 279 hours. It is also the half of the year outside the cyclone season.
Within that span, October is the calendar's best month: 15 millimetres, 3 rain days, 279 hours of sun and 28.8 degrees by day. September and November follow closely, at 17 and 24 millimetres. If you prefer less heat, July and August stay at 26.7 and 26.8 degrees by day.
The months to avoid are January, February and March, for the combination of rain, mugginess and cyclone risk. December is more ambiguous than it looks: 85 millimetres fall but it accumulates 279 hours of sunshine, the same as October. And there is one figure worth keeping in mind in any month: relative humidity does not drop below 74 % all year.
