Mexico's rainy season, coast by coast

When is the rainy season in Mexico?

In the areas where owners have houses it runs broadly from June to October, the five months in which most of the year's rain falls. It does not end on the same date everywhere: on the Caribbean coast the wet months stretch into winter, and in Baja California Sur the season is little more than August and September.

The rainy season in Mexico has no single official calendar. What exists are the climate normals of each weather station, kept by the Servicio Meteorológico Nacional for the thirty years from 1991 to 2020 and reissued on 16 October 2026. Adding the months from June to October in five of them gives the share of a normal year's rain that falls in those five months: 93% in Acapulco, 86% in Cabo San Lucas, 81% in San Miguel de Allende, 64% in Tulum and 59% in Cancún.

So the honest answer to when the season comes is a question in return: which coast. On the Pacific and in the highlands, the dry half of the year is genuinely dry. On the Caribbean, it is only less wet.

Why does it differ between the Caribbean, the Pacific and the highlands?

Because each faces a different sea and a different storm season, and the highlands sit almost two thousand metres above both. The stations show three patterns: a short, intense summer on the Pacific, a long wet year with a peak in autumn on the Caribbean, and a moderate summer season inland.

Acapulco is the clearest case of a Pacific summer: its station records 0.2 mm in April and 281 mm in September, and fewer than one day of rain a month from December to April. Its year is in the guide to Acapulco weather.

The rainy season in Mexico's Riviera Maya is the opposite shape. It has no month without rain: Tulum's driest is March, with 33 mm over 2.9 days, and in Cancún January alone brings 103.8 mm over 9.8 days. The month by month is in the guides to Cancún weather, Tulum weather and Playa del Carmen weather, which lies on the same coast between the two stations.

San Miguel de Allende has a summer season of its own, smaller in volume: 146.8 mm in July, 5.5 mm in December. What that does to a stone house on dry ground is in the guide to San Miguel de Allende weather.

How does it overlap with the two hurricane seasons?

Almost completely, but not on the same dates: the eastern Pacific season runs from 15 May and the Atlantic season from 1 June, and both end on 30 November. The months of heaviest rain in every area of the table fall inside the storm season of its coast.

The National Hurricane Center gives both calendars: the Atlantic hurricane season runs from June 1 to November 30, and the eastern Pacific hurricane season runs from May 15 to November 30. Mexico's civil protection agency, CENAPRED, uses the same dates, and adds that this no descarta que puedan producirse ciclones fuera de estos meses, pero es más rara su aparición.

The peaks differ too. On the Atlantic side, the NHC places the peak of the season on September 10, with most activity between mid-August and mid-October, which is also when Cancún and Tulum record their wettest months. In the eastern Pacific the peak is less pronounced, with most tropical cyclones occurring between late June and early October.

Rain and storms are not the same thing, and an owner needs both calendars: the rain says when the house is tested most often, the storm season when it can be tested hardest. What the storm season means on each coast is in the guides to hurricane season in Cancún, hurricane season in Cabo San Lucas and hurricanes in Acapulco.

What does Los Cabos's short rainy season look like?

It is two months long and very light by the standards of the other coasts: 258.6 mm in a normal year, of which 190.4 mm fall in August and September. The rest of the year is close to dry, with no rain at all in a normal April.

The rainy season in Cabo San Lucas, Mexico, is the shortest of the areas in this guide. The station at Cabo San Lucas, fifteen metres above sea level, records 76.4 mm in August, 114 mm in September and 13.3 days with rain in the whole year, against 0 mm in April and 0.1 mm in May. August and September together hold nearly three quarters of the year's rain.

Short does not mean mild. In a desert that sees rain on thirteen days a year, the water arrives in few events, and those months fall inside the eastern Pacific hurricane season. A drain that has carried nothing since October, or a roof that has baked since March, is tested on a single night. The month by month is in the guide to Cabo weather, and the coast's storms in the guide to hurricane season in Cabo San Lucas.

What does the season do to a house nobody is living in?

It turns small faults into damage, because nobody is there to notice them: a blocked drain, a crack in the roof membrane or a window left ajar lets water in, and the water stays. In a closed house the problem is less the rain itself than the days after it.

The United States Environmental Protection Agency advises drying water-damaged areas within 24-48 hours to prevent mold growth and keeping indoor humidity below 60 percent (ideally between 30 and 50 percent). In an occupied house, someone mops the floor and runs the air conditioning. In a house that stays closed through a Caribbean October, with 16.4 days of rain in Cancún, neither happens until somebody arrives.

The damage follows the shape of each coast's season. On the Pacific and in the highlands it is concentrated: a few months in which roofs, drains and gutters work hard after half a year of dust. On the Caribbean it is continuous: the air never fully dries, and a closed room collects moisture in every month of the year.

What is arranged before it, and checked after?

Before, the parts of the house that carry water — roof, drains, gutters, openings, shutters — are checked and cleared by the start of the storm season of that coast: mid-May on the Pacific, June on the Caribbean. After, the house is opened, aired and inspected within days of any heavy rain, not on the owner's next visit.

For an owner who is away, the list is short and has dates on it. None of it is urgent on the day it is agreed, which is why it is worth agreeing in advance.

That is maintenance with a calendar, which is what preventive maintenance means in practice, and what an annual plan lays out across the twelve months of each coast. What is found and what is spent goes into the monthly owner statement, so that a storm in October has a record by November.