The year in Baja California Sur, month by month
The figures come from the La Paz station, 1991–2020 series of Mexico's national weather service: 185.5 millimetres a year over 26.9 days and 3,112.6 hours of sun. The scoring crosses rain, temperature, humidity and cyclone risk.
There are dry destinations and there are destinations where rain is, simply, an accident. This is the second kind, and that completely changes the question to ask before booking.
The question is not whether it will rain. It is how much heat you will take, what temperature the water will be, and whether you land in the one month of the year when the sky can genuinely turn.
01 One point seven millimetres in four months
The figures from the La Paz station are almost comic: 0.8 millimetres in March, 0.2 in April, 0.2 in May and 0.5 in June. Across the four months, 1.7 millimetres over a little more than two rainy days in total.
The full year comes to 185.5 millimetres over 26.9 days. That is, on three hundred and thirty-eight days of the year nothing falls at all, and sunshine accumulates 3,112.6 hours, over eight and a half a day on average.
That is why the landscape is what it is. With those amounts there are no permanent rivers and no meadows, but thorn scrub, cactus and bare ground, and green only appears for a few weeks after a storm goes through.
One point seven millimetres in four months. There is no rainy season: there are isolated storms.
02 And 44 per cent of the year in September
Against that void, September leaves 81.4 millimetres over 6.3 days. That is 44 per cent of all the year's water concentrated into a single month, and August adds another 45.5 over the same number of days.
Adding July and October, the four months of late summer and early autumn gather 155.9 millimetres: 84 per cent of the total. And that water does not fall in scattered showers but in a few large episodes.
The reason is the one on this article's cover: tropical cyclones that track up the eastern Pacific and graze or cross the peninsula. A single system can leave more in a few hours than falls in an average year, with the month's humidity at 72.6 per cent.
03 Thirty-eight degrees in July
The other figure that rules is heat. July's mean high is 38.2 degrees and August's 37.8, with an absolute record of 44.0 set in July. June is already at 37.4.
What makes summer worse is not only the ceiling but the floor. August lows sit at 25.2 degrees and September's at 24.7: the night stops being a rest, which is exactly the opposite of what happens in an inland desert.
The compensation is the sea. In those same months the water is at its warmest of the year, so summer is not useless: it is a different trip, in and out of the water, up early and with no pretence of walking at midday.
04 The winter that is not like a winter
From December to February mean highs run between 25.4 and 26.5 degrees, and lows between 12.3 and 12.8. That is, the worst month of winter resembles a mild May at mid latitudes.
Winter rain is symbolic: 9.3 millimetres in January, 5.5 in February. The only thing that really drops is light, with 194.9 hours of sun in December, the annual minimum, which is still over six hours a day.
What does change is the water. In winter the sea cools and swimming stops being automatic, above all on the Pacific side, where the current is cold all year. For a lot of swimming, autumn wins; for walking, winter.
05 The whales set the calendar
In this state there is a second layer of calendar that depends not on the thermometer but on migration. Gray whales leave the North Pacific in October and reach the lagoons of the western coast between mid-December and January.
The bulk of the population is inside between mid-February and mid-March, which is when the lagoons fill with calves. From then on they start to leave, first the males and the females without calves, and the mothers last.
So the real window is December to April, centred on February. And it coincides exactly with the months of best air temperature, which makes that stretch the state's obvious high season.
06 How to choose the month
If you come for the whales, January to March, no argument. It is also the stretch with the year's most comfortable temperatures: highs of 25.4 to 29.3 degrees and practically zero rain.
If you come for the water, November and October. The sea is still warm from summer, rain has already dropped to 6.2 and 17.3 millimetres, and highs come down to 29.8 and 34.0 degrees. It is the best combination of air and water temperature the year offers.
And if you can only travel in summer, avoid September above all. July and August are hard for the heat, but predictable; September concentrates 44 per cent of the annual rain and the highest risk of a cyclone changing your plans at a stroke.
The year's four stretches
From 0.2 to 9.3 millimetres a month, with highs of 25.4 to 32.2 degrees and 194.9 to 292.9 hours of sun. It coincides with the whale season in the Pacific lagoons.
0.2 and 0.5 millimetres, with 323.2 and 308.2 hours of sun and highs of 35.3 and 37.4 degrees. Dry and bright, but midday is no longer walkable.
138.6 millimetres across the three months, with 81.4 in September alone. Highs of 35.9 to 38.2 degrees, lows up to 25.2 and humidity of 72.6 per cent.
17.3 and 6.2 millimetres over 1.8 and 1.2 days, with highs of 34.0 and 29.8 degrees. The water keeps summer's heat and the cyclone risk fades.
