Oaxaca month by month — at a glance
Hover each month for the summary. Click to pin it.
Oaxaca sits almost in the tropics, but 1,555 metres up. That combination produces an odd year: the temperature barely moves and yet the landscape changes completely, twice. Anyone picking a date by the thermometer is reading the wrong instrument. Here you read the rain gauge.
01 The thermometer barely moves
The year's lowest average high, in December, is 28.9 degrees. The highest, in April, is 34.9. Six degrees of travel across twelve months. The lows do something similar: 10.3 in January, 16.7 in May and June. It never freezes and it is never impossibly hot.
That means no month is ruled out by temperature. You can walk the valley in January and in August in the same clothes, save for a light jacket on winter nights. The decision, then, is played out elsewhere.
Key moments at a glance
An average high of 34.9, the year's peak, with the valley still brown. Visit from seven to eleven and again after five.
188.3 millimetres, the annual maximum. All green, all wet, and the mountain tracks at their worst.
63.1 millimetres and the countryside still coloured by six months of rain. The shortest window and the most rewarding.
9.1 millimetres, 29 degrees by day and 12 at night. Clean skies without the spring heat.
02 April, not July
Almost everyone assumes summer is the hottest part of the year. In Oaxaca it is not. The heat peaks in April, with an average high of 34.9, and from there the curve falls: 33.8 in May, 30.9 in June, 30.1 in July. July is five degrees cooler than April.
The explanation is simple and has practical consequences. In April the sky is clean and the sun beats down unfiltered for twelve hours straight over a valley with no humidity. In June, afternoon cloud covers the sun almost daily. It is not cooler because winter has arrived: it is cooler because there is a ceiling.
In Oaxaca the summer does not bring heat. It brings shade.
03 Five months without rain and two with almost all of it
The distribution of water is brutal. From November to March a total of 42.7 millimetres falls — less than a single June day — while June and September together bring 351.9. Put another way: two months of the year hold more than forty per cent of the annual rain.
In practice this produces two different Oaxacas. The dry-season one is ochre: cut fields, brown slopes, hard light, dust. The wet-season one is green and dense, with low cloud wedged between the ranges. Neither is the correct version; they are two destinations sharing a postal address.
The rain, moreover, almost never lasts all day. It falls in the afternoon, in storms of an hour or two, leaving the mornings clear. The problem is not getting wet: it is that mountain roads degrade, and a landslide can close a whole valley for hours.
04 The July gap
Inside the wet season there is a useful anomaly. June delivers 188.3 millimetres, July drops to 118.6 and August climbs back to 131.8 before September's peak. That midsummer dip is known in Mexico as the canícula or veranillo, and it happens when anticyclonic systems suppress storm formation.
It is worth saying carefully: the canícula has no fixed dates, lasts as long as it lasts, and in some years simply does not appear. What is constant is the average: July rains a third less than June. Which is why the month that holds the city's festivities — the Guelaguetza falls on the two Mondays closest to 16 July — lands right in the breather.
The price of that coincidence is a full house. In those two weeks the city's occupancy multiplies, accommodation prices rise and tables need booking. If you are going for the calendar, go; if you are going for the landscape, there are better and far cheaper months.
05 October and November: green and dry at once
The year's best combination lasts about six weeks. In October the rain withdraws abruptly — from 163.6 millimetres in September to 63.1 — but the countryside takes weeks to dry out. It is the only time you can have a clear sky and a green valley at once.
November finishes the window: 9.1 millimetres, 29 degrees by day, 12.3 at night, and the ranges visible from the valley first thing. It is also the month when April's heat is still a long way off, five months ahead.
06 How to pick the week
If you are going for the markets, the workshops and the city, any dry month works: from November to March the valley is brown, but a covered market does not care, and the roads are at their best. December, January and February are the easiest months for walking all day.
If you are going for the landscape and the mountains, aim at the second half of October. If you must travel in the wet season, June and September are the two months to dodge, and August is the most workable of the wet ones: it rains in the afternoon, not the morning.
And if you go in April, change the timetable instead of the date. With highs of 34.9, the usable day runs from seven to eleven and from five until dark. In between, the valley stops, and rightly so.
