Oaxaca's Wonderful Weather
Beautiful Oaxaca - La Tierra del Sol or Land of the Sun - enjoys near perfect weather year round, with tropical sunlight almost daily and ideal temperatures. This privileged climate is a result of various factors.
Located between latitudes 15º and 18º north of the equator, Oaxaca is a bit of paradise enmeshed in the Sierra Madre mountains and bathed on its southern shore by the blue Pacific. Altitudes range from sea level on the coast to 3720 meters (12,205 feet) above sea level at the highest point (Cerro Nube in the southern mountains near the coast) and include every possible height in between, making a myriad of pockets and valleys with highly diversified microclimates.
Most of the state is classified as temperate with ample rainfall in season, with sections ranked as dry, and the coastal plain plus a good part of the southern mountains as hot with rainfall in season. Average annual rainfall is 800 mm (31.5 inches) along the coast and 750 mm (29.5 inches) in the central valleys, falling almost entirely during the official rainy season of May to September. Relative humidity in the city varies from an average 15-40% October-May to an average high at the peak of the rainy season of 80%, while on the coast it hovers around 80% most of the time, getting up to 100% during a rainstorm.
Its position between the Pacific Ocean and the Gulf of Tehuantepec on the south and the Gulf of Mexico just a few kilometers to the north, attract humid air currents which swirl around the Isthmus and the mountains influencing the weather patterns within the area, with winds of 60 kph gusting to 200 kph in La Ventosa, and creating the "nortes" which cause the relatively few really cloudy days throughout the year.
Here are some statistics courtesy of the National Meteorological Service's Oaxaca Station, based on daily records over a period more than 20 years and averaged to provide a mean. Obviously, there are years when there is more or less rain, higher or lower temperatures and other differences from this mean. We will discuss below how some of these numbers translate into comfort factors.
Days of sun per year
Overcast days per year
high 34º C (93º F)
low 11º C (41º F)
high 36º C (96º F)
low 25º C (77º F)
These are official average figures which may vary in some years or on some days but give a good overall idea of the weather patterns. What do they mean in terms of comfort for us and how can we expect seasonal variations to affect us? To determine this we must keep in mind some very important details.
First, average high and low temperatures only apply to a couple of hours at midday and late night/predawn. Most of the day in the central valleys the temperature will be around 25º C (77º F) to 30º C (86º F). Remember, in the capital city of Oaxaca we are at an altitude of 1550 meters (5080 feet) above sea level which means that the sun is near and quite strong but that there will always be a significant difference in temperature out of the direct sun precisely because of the altitude. If you plan to be in exposed areas, such as Monte Alban, wear a hat and if you feel the heat just find a shady spot outdoors or rest indoors for a short time. After all, the siesta was invented to relax and enjoy the middle of the day.
At night in the city the temperature is always cool enough that you should have a light wrap if you plan to be out, especially if you are sitting around the zócalo with its trees, thick stone walls and portales which cause us to feel cooler than the actual temperature of the air.
There are a few nights, especially in January, when the temperature may get down to an extreme low of 5º C or so but these are isolated occasions. Just so are the extreme highs which may occur just before the rains begin. (As a point of information, the highest and lowest temperatures recorded in the city of Oaxaca are 40.2º C (104.5º F) and 2ºC (35.6º F) - both one time events.)
There may be two or three torrential rains, possibly even with hail in some areas, in April or May when warm humid air meets the cooler air but the rainy season usually doesn't get under way until around the middle of June and lasts until late September or the beginning of October. During this time the mornings and early afternoons are sunny and warm until the clouds begin to gather over the mountains and the showers quickly follow and as quickly pass on, leaving everything refreshed and gleaming. It is easy to see when the rain is approaching, but an umbrella or raincoat is advisable in case a shower moves faster than you do. Once in a while a soft rain will fall well into the night to nourish the earth and plants but usually the showers are brief and the sun comes back out to finish the day.
As you can see, Oaxaca is indeed privileged in many ways, not least in its weather. Low humidity, comfortable temperatures, light breezes from the northeast at around 2 meters per second (about 4 mph) and beautiful sunlight nearly every day. Just remember to take things easy your first few days until you become accustomed to the altitude, protect yourself from direct midday sun and you will feel ready to climb pyramids, tour the city and visit the markets, the nearby artisans' villages and natural attractions and still have plenty of energy to dance or enjoy concerts and people-watching at the zócalo every night.
And the nights - ah, those soft, tropic nights of brilliant stars when the moon illuminates the mountains and the fragrance of flowers fills the caressing air. When a full moon lends touches of pearl to all it touches and perhaps a stray wispy cloud gives a touch of mystery to the inky sky.
At sea level, there is really little difference between high and low temperatures and sea breezes play an important part in making us feel cooler, especially on one of Oaxaca's 500 kilometers of beaches. Even there, if you are outside at night a light wrap can be very welcome. The rain on the coastal plain is most concentrated in August and September and can be quite sudden and heavy although shortlived and not unpleasant.
Enjoy the beach areas of Puerto Escondido, Puerto Angel and Bahías de Huatulco and all their nearby attractions such as the Laguna of Manialtepec, the turtle reserve at Mazunte, as well as the Isthmus with Tehuantepec, Salina Cruz, Juchitan and many other places of interest.
Wherever you may visit in our Land of the Sun, you will find a local variation of Oaxaca's Wonderful Weather. Enjoy it.