Mazatlán, where it's located

The climate of Mazatlán is sub-tropical, with a quite warm winter from December to February, and a hot summer from May to November, within which there is a rainy and muggy period from July to mid-October.
The city is located on the coast, in the state of Sinaloa, at the Tropic of Cancer, more or less at the latitude of Cabo San Lucas (i.e. the southernmost part of Baja California). From July to October, in the rainy period, the humidity increases and the heat becomes decidedly unpleasant.
In winter, in some years the temperature never drops below 10 °C (50 °F), but every now and then, a mass of cold air from the United States can bring some cold at night. In February 2011, the minimum temperature dropped to 3 °C (37.5 °F).
On the hottest days, from June to October, the temperature can reach 37/38 °C (99/100 °F).
In theory, Mazatlán can be affected by hurricanes of the Pacific Ocean from June to November, however, they generally pass further west, along the California Peninsula; moreover, historically they never occurred in November. As a result, the city was hit very rarely: by Hurricane Mazatlán in October 1943, by Hurricane Olivia in October 1975, and by Hurricane 12 in October 1957.
The average temperature of the coldest month (February) is of 19.8 °C (68 °F), that of the warmest month (August) is of 29.3 °C (85 °F). Here are the average temperatures.
Mazatlán - Average temperatures
Min (°C)131314162024242424231915
Max (°C)272627293133343434333128
Min (°F)555557616875757575736659
Max (°F)817981848891939393918882

Precipitation amounts to 845 millimeters (33.3 inches) per year: so, it is at an intermediate level. It ranges from 0 mm (0 in) in the driest month (April) to 255 mm (10 in) in the wettest (August). Here is the average precipitation.
Mazatlán - Average precipitation

On average, there are around 2,890 sunshine hours per year. Here are the average sunshine hours per day.
Mazatlán - Sunshine

The sea temperature ranges between 22.5 °C (72.5 °F) and 30 °C (86 °F). The sea is pleasantly warm from June to November, while from January to March, it is a bit cool but all in all acceptable for swimming. Here are the average sea temperatures.
Mazatlán - Sea temperature
Temp (°C)232223242628303030302725
Temp (°F)737273757982868686868177


Best Time

Mazatlán can be visited from December to March, as it is the mildest season. During the day you can enjoy the sun, while in the evening you will need a sweatshirt and a light jacket.
For a beach holiday you may prefer May and November.