Mexico - weather in September

September is the first autumn month in the Northern Hemisphere, however, in Mexico, a very large country crossed by the Tropic of Cancer in the central part, it is still a hot, muggy and rainy month in the center-south. In the north, on the other hand, temperatures begin to decrease, however, September is a hot and sunny month, with possible thunderstorms in inland areas.
At low altitudes, the temperature is warm, and not too hot, only on the north-west coast, exposed to the Pacific, where a cold current flows (see Tijuana, Ensenada). Instead, in the south, in the tierras frìas (see Mexico City), the temperature is not too high because it is mitigated by the altitude.
Especially in inland areas and at low altitudes, heat waves can occur, during which the temperature can reach and exceed 40 °C (104 °F).
The rains are very rare or completely absent in the northwest, in Baja California.
On the other hand, in the Sierra Madre Occidental and in the Chihuahuan desert, thunderstorms can form, brought by humid air coming from the Pacific Ocean ("North American monsoon"). In Baja California South, in the southern part of the California peninsula, rare rains occur, which become more frequent in inland hilly and mountainous areas.
In the south, the rains are abundant everywhere.
On the coasts of the Gulf of Mexico, also in Yucatán and the Riviera Maya, the rains are abundant, actually, this is the month in which the rains are more abundant in the areas exposed to easterly winds. On average, in any case, September is the wettest month of the year in Mexico.
From June to November is the season of hurricanes, which mainly affect the coasts of the Gulf of Mexico and the southern Pacific coast, but sometimes they can also affect the north-west, i.e. the California peninsula, or they can penetrate inland. September is the peak of the period when hurricanes are more frequent, which runs from August to October.

The sea is warm enough for swimming everywhere, except in the northern part of the Pacific coast (see Tijuana, Ensenada), where it is very cool due to the already mentioned cold current.




See also: Mexico, the weather in August - October
The climate of Mexico