The northern state of the peninsula, Baja California can be divided into three weather regions, the Pacific coastal region, the Inland region and the Sea of Cortez region. With the Pacific Ocean much cooler than the Sea of Cortez these three regions can vary in temperature 30°F or more on any given day. Rainfall and cloudy skies are much more prevalent in Ensenada, while scorching temps and crystal blue skies are found about 200 days a year just 80 miles inland. The northern Sea of Cortez is the third climate area in the region, but tends to be more similar to the inland areas, particularly when it comes to defining HOT!
Baja California is more affected by winter storms from the Pacific and the region's rainy season would best be defined in the winter months. It is very rare for a tropical cyclone to make landfall from the south in the state, although the remnants have sometimes brought intense rain to the region as the storms break up and move into the southwest U.S.
Snow can be found on a rare occasion in the mountains near the border during the winter and the hottest temperatures of the summer can be found in the inland deserts, where 110° isn't unusual in June and July.
Coastal cities include Tijuana, Ensenada, Colnet, San Quintin and El Rosario. Inland cities are Tecate and Mexicali. Cities on the Sea of Cortez are San Felipe and Puertocitos. The developing wine country is located in the higher elevations between Ensenada and Tecate, and some of the oldest wineries in Baja dating back to the 1600's are in Santo Tomas, just south of Ensenada on the Pacific coast.
As Summer gives way into Fall, the weather influences slide into neutral again. The summer heat begins to break and it is one of the best times to visit anywhere in Baja.
Northwest: In the early fall, beginning in September, the Pacific coastal areas are alive with sport fishing as the temperatures cool into the low 80's. Off-shore winds provide clear skies and even inland temperatures moderate by mid October. The Pacific coastal areas are alive with bicycle rallies, concerts and the events of wine country. Fall in this region runs from late September through the mid of November. Then the first winter storm moves down the California coast and we start the cycle all over again.
Northeast: Mexicali stays warm during the day long after most other places in Baja, as the desert southwest flow continues to pump warm air into the region. By late October the region begins to cool and off-road enthusiasts gather for the Baja 1000. By early December the high desert can start to get pretty cool in the upper 60's and the nights quite brisk.
The northern state of Baja California offers a wider variety of climates on any given day, than her sister state to the south. This is because the Pacific Ocean only approaches the 70°F degree mark in the warmest parts of summer, while less than 100 miles away, the Sea of Cortez can be in excess of 90°F. The state boasts one of the hottest places in Mexican summers and is also one of the few states that receives snowfall in the winter. The state receives more than twice the amount of yearly rainfall as does Baja California Sur.
In winter our weather patterns across the peninsula come from the north. Pacific storms can bring showers to a full blown downpour to any region of the peninsula, but the chances and the ferocity of the storms diminish as you move south.
Caused by High pressure moving over the 4 Corners Region of the U.S., north winds play a strong role in defining the northern winter climate on any given day. Winds can whip up well over 30kts for a several days straight. The winds pump cold air south into the trough which exists almost perpetually down the center of the Sea of Cortez. but they also create an off-shore flow along the coast, bringing winter time high temps in the mid to upper 70's for several days at a time to Tijuana and Ensenada.
Northwest: In the Pacific costal areas of Baja California winter begins with the first rain storm that works its way down the Pacific coast of the United States. This can occur anytime after early November, but can hold off well into the New Year on occasion. In December coastal daytime highs can be very pleasant. When off-shore winds develop temps can reach into the upper 70's. Nights can be quite cool, with clear skies and intense radiational cooling with temps in the 40's and damp. During these Santa Ana wind periods the best weather on the peninsula can be along the Pacific coastal areas.
February brings the peak of winter precipitation to the coastal areas and rains can be very heavy at times. Unpleasant weather can hang on for a week or so at a time, then be broken with clear skies and temps climbing into the mid to upper 60's and low 70's. The Pacific can yield some dramatic surf, churned up by massive winter storms moving across the Pacific. But that Pacific water is COLD and you usually only find tourists from the most northern climates finding it inviting. Oh yes, let us not forget the surfing crowd, one of the largest waves ever surfed was conquered on the west side of Isla Todos Santos just west of Ensenada.
Northeast: The winter rains move south along the Pacific coast and don't make it to Mexicali very often. The desert can be sunny and cool during the day with temps in the upper 60's to upper 70's, but nights can be cold, often near or below freezing at the coldest point in the season. As the region extends down onto the Sea of Cortez and San Felipe, this region has long been a haven for snowbirds and their RV's as a refuge from winter's cold. But even the Sea of Cortez has a hard time moderating the radiational cooling that occurs at night, with clear skies. Temps can plummet to the near freezing point for a few weeks during the depths of winter in late January and February.
In Winter the weather comes from the north in Baja, in summer, from the south. Spring and fall represent periods when our weather doesn't come from anywhere at all, a never-never land between northern and southern influences.
Northwest: Spring comes to the Pacific coastal areas slowly, as Pacific winter storms lose their punch further and further to the north along the California coast. A played out storm may bring showers to the region into March, but by late in the month spring has sprung. Because of the cold Pacific waters Spring may be the longest season along the coast, and perhaps the most unpleasant for the region. Low pressure, caused by warming air over inland deserts, draws moisture inland. Mornings bring dense overcast and fog as the two air systems meet. Early in the season this may persist through much of the day before clearing. It rolls back in again in the late afternoon. Fog as far south as Guerrero Negro and San Ignacio can be very dense in the morning hours. Semi affectionate names like May Gray and June Gloom make light of the lack of sun, but by July the morning overcast is appreciated, keeping things cooler. Temperatures range in the low to upper 70's during the day, into May. Overnight lows begin to moderate in the upper 50's by late March.
Northeast: Spring is a volatile time on the inland areas with a daily temperature variation as much as 30° to 40°F. Things begin to warm up by mid March, which is why the RV crowd peaks during that season in the region. By late March Mexicali can see temps near 90°F daily. But with strong radiational cooling overnight, things get quite brisk until late March as well.
As the airflow begins to moderate, the northern portions of the Sea of Cortez warm up quickly. High pressure systems move progressively north of the 4 Corners Region and by the first of March things start to warm up. By late in the month temps into the 80's are the norm and winds from the NNW around 15kts make the days great for outdoor recreation.
Summer is hot in Baja, there is no denying that. In Summer you could most aptly divide Baja into East and West. The Pacific keeps the western portion cooler, with winds from the northwest into July. The eastern side of the peninsula warms up quickly as the shallow Sea of Cortez warms. Inland, with no body of water to moderate the temperature highs can reach well over 100° for months at a time and cooling at night is very limited. Thunderstorms are common in July through Septembert.
There have only been a couple of landfalls of tropical cyclones in Baja California in the last 50 years, and both were just tropical storms. But the remnants of hurricanes in the south sometimes drift across the northern state and deliver significant quantities of rain and have washed out bridges and roads, causing by-passes and temporary road closures in August and September. Campers should be aware of the possibility of flash flooding in arroyos miles away from the rainfall that may have caused them in the late summer months.
The Pacific coastal areas, particularly Ensenada and southward are a summer haven for those looking to escape the heat. Temperatures along the coast can be as much as 20°F cooler than just a few miles inland. Inland to Mexicali and southward along the Sea of Cortez, summer can be just plain oppressive with daytime temperatures well over 100°F.
Northeast: Pacific waters keep the coastal areas cooler, with temps regularly in the mid 80's. This is one of the most popular season to visit the region as folks from central California and warmer regions of Baja find the weather most appealing. Skies clear progressively earlier along the coast. Inland just a few miles temperatures can be +10°F warmer. Thunderstorms are not unusual by late July.
Northwest: Mexicali reaches infernal temperatures by late May and triple digits are a constant through October. Overnight lows are a dramatic change in early summer but with increasing humidity by late July, things moderate to just plain hot all the time. Thunderstorms are common, drifting west from the Sonoran desert that can deliver high winds and short intense periods of rain. Flash flooding can occur and cause temporary road closures.
So with so many climate options you should be able to find your favorite place to play on the Baja peninsula, almost any time of year.
Also see: When is the best time of year to visit Baja California Sur?