Yucatán month by month, at a glance
Figures for Mérida, 1991-2020 series. Hover over each month.
In Mérida not one month of the year has a mean maximum below thirty degrees. The coolest is December at 30.7; the hottest, May, at 36.7. Six degrees of range across twelve months, all of them above the threshold where you decide whether to walk or not. That simplifies the question: here you do not choose the date by temperature, because there is no choice. You choose by water, by cyclones and by two specific days in the calendar.
01 There is no cool month
The figures are for Mérida, the 1991-2020 series. Mean maxima: 30.8 in January, 32.1 in February, 34.5 in March, 36.3 in April, 36.7 in May, and from there a plateau of 35 degrees through August, easing in October and November. Minima run from 16.9 to 22.8.
That floor of sixteen degrees on the coolest night of the year, with maxima of thirty-one, is the closest thing the state has to a winter. And in practice it is the best temperature for visiting ruins: from December to February you can stand in the sun at midday, which is exactly what Uxmal or Chichén Itzá require.
02 What does change is the water
The annual total is 996.5 millimetres over 87.9 rain days, but the distribution is what matters. From February to April it brings 26.7, 26.4 and 25.0 millimetres, on two or three rain days a month. From June to September, 152.0, 143.1, 152.3 and 184.2, over eleven, twelve, twelve and thirteen and a half days.
So the state has a genuine dry season — November to April — and a wet one that holds nearly everything. In the dry, the landscape turns yellow and the sky stays clean; in the wet, everything greens and the afternoon storm is the norm. Neither is bad; they are two different places.
03 Hurricane season runs from 1 June to 30 November
That is the Atlantic's official window, and the peninsula sits squarely on the usual tracks. The most active period concentrates between mid-August and late October, which coincides with the wettest months.
It does not mean a September trip will meet a hurricane: it means taking insurance with weather cover, not stacking flights with tight margins and accepting that a day of the trip may vanish. September, at 184.2 millimetres, combines the maximum rainfall with the maximum risk.
Key moments at a glance
32.1 °C maximum, 26.7 mm over 3.1 days and outside hurricane season.
26.4 mm over 2.4 days, but the equinox fills Chichén Itzá on the 20th or 21st.
36.7 °C mean maximum, the year's peak, with the rain beginning.
184.2 mm over 13.5 days and the height of the hurricane season.
04 Two days that fill an entire site
And here is the factor that is not in the table. At the equinoxes — 20 or 21 March and 22 or 23 September — as the afternoon falls, the sun casts on the stairway of the Kukulcán pyramid at Chichén Itzá a run of seven triangles of light and shadow which for some forty-five minutes draw the body of a serpent descending. The phenomenon was described in an academic study in 1969.
The effect on a trip is one of crowds. Chichén Itzá received its 2,200,000th visitor in 2024 and is Mexico's most visited archaeological site; at the spring equinox a disproportionate share of that figure concentrates into a few hours. If the aim is to see the phenomenon, go knowing what it involves. If it is not, those days are best spent elsewhere in the state.
05 The state's only thermostat
There is one compensation that works all twelve months. The groundwater holds a practically constant temperature all year, so a cenote is as cool in February as in August. In mid-May, with 36.7 degrees above, dropping twenty metres into a flooded cavern is the difference between being able to be outdoors in the afternoon and not.
That reorders the day in the bad months: ruins and villages first thing, cenote at midday, and out again as the afternoon cools. It is the same scheme used anywhere with extreme heat, except that here the shade is underground and has water in it.
06 The honest summary
December to February, without argument: maxima of thirty or thirty-two degrees, minimal rain, no cyclone risk and grass still holding some green. March and April are still dry and already hard, with the equinox days as the exception.
May is the worst month for temperature and September for water and risk. And July and August, wet as they are, have an advantage almost nobody mentions: they are when the state is greenest and has fewest foreign visitors, and when the cenote stops being an excursion and becomes the centre of the day.
