The Tropic of Cancer passes through Todos Santos, some 50 miles north of Cabo San Lucas. Although nearly surrounded by ocean, Los Cabos is in the "dry" tropics, where the sun is hot and rain is scarce. Los Cabos' weather is influenced primarily by its tropical latitude and the effects of the surrounding ocean on local weather patterns. Weather is mild, sunny and dry most of the year, hot and sometimes stormy in the summer.

Conditions can vary widely, depending on location, time of day, and proximity to ocean and desert. The Pacific Ocean side of Cabo San Lucas, for example, is often ten degrees cooler than the downtown marina area, which Cabo's hills protect from chilly Pacific breezes. San Jose del Cabo, on the Sea of Cortez just 20 miles northeast of Cabo San Lucas, is often a few degrees warmer than San Lucas. Todos Santos, fifty miles north on the Pacific coast, is usually much cooler. Fog is rare in San Jose and San Lucas, but common a few miles north, along the Pacific.

Wind direction is a big factor in the weather. Different levels of humidity and temperature occur when the wind blows from the desert and mountains, the Pacific Ocean or the Sea of Cortez. In the winter, the prevailing westerlies bring cool, dry Pacific air from the west and north. In the summer, the trade winds shift and carry storms and moisture from the south and east. The time of day also affects wind direction. Dry desert breezes are common at night, when warm air rising above the ocean draws cool air from the land. Moist sea breezes prevail when the desert heats up during the day, causing air above the land to rise and draw an onshore flow.

Reliable long-term weather data is nonexistent in many instances, and inconsistent or inaccurate in others. Records have improved in recent years, as Cabo San Lucas and San Jose del Cabo have blossomed on tourist and political maps.

Winters are sunny and mild. The summer moisture is dried, and skies are mostly clear. Daytime high temperatures are usually in the 70's (f.). Nights range in the 50's and 60's. Mid-winter nights can sometimes drop into the 40's, and, rarely, even into the 30's. Freezing is unknown at the beach, but frosty nights are common in the nearby Laguna Mountains, where elevations rise more than a mile above sea level.

Spring is the driest season. Most years, there is no rain at all from March through June. Winter blends almost imperceptibly into spring, and temperatures rise gradually with the approach of summer.

Los Cabos is hot in the Summer. From June through September, most days are in the 90's, sometimes topping 110 degrees inland, but seldom over 100 near the ocean. Ocean water temperatures can rise above 90 degrees. Nights are increasingly warm and humid as August approaches. Summer is the "rainy" season. August and September (hurricane season) are the rainiest months, although they combine for less than three inches on average. Humidity hangs in the 70's.

Autumn brings abrupt change. Weather remains warm and muggy until the ocean currents begin to cool in mid-October. October is the major transition month, as the trade winds reverse direction and weather patterns shift. Nights are cool again, and people stop sweating. The change can be remarkably sudden, but is always welcome. Although infrequent, rain is more likely in the autumn than in the spring.

Annual rainfall averages less than seven inches, and most of that can fall during one or two storms. However, "average" precipitation figures can be misleading. A single year with a major rainstorm can disguise a lot of very dry years. The annual average rainfall of more than 30 inches in the Laguna Mountains provides Los Cabos with fresh water, but the supply is limited. Water is always precious in this tropical desert.