If you have been following the series of articles on RVing Mexico you may have encountered information regarding climate that states there is a huge variation in temperature and humidity because of large variations in elevation. A mere three hours travel time means that I no longer need fans and just a sheet at night but a heater and sweat pants and shirt at breakfast.

HOW TO USE THIS ARTICLE

There are a number of differences between the dry winter season and the moist summer. Dry weather doesn't require much of an explanation but I felt as though simply stating "rain" or "tropical storm" isn't enough---aware travelers should understand a little of the "how" and "why" behind the fact. Mexico in the summer is definitely different than it is in the winter. Most of it has to do with rainfall but specifically it is what kind of weather system the rain is coming from that should be of interest to all RV'ers.

IT'S NOT A SIMPLE MATTER OF "STEAM OR SHIVER"

Except for the Yucatan peninsula, you can use any map of Mexico and then "shade" a half-inch border along the coastlines. This would be the tropical lowland. Inland from that rapidly rising terrain may be as radical as my three-hour drive and seven thousand feet gain in altitude. In fact, the entire "center" of interior Mexico is well over five thousand feet in altitude. Yucatan on the other hand is as flat as a pool table.

Many RV'ers choose Mexico especially for it's inviting climate. It would be lazy of this writer to not include a healthy dose of descriptions of climactic conditions in Mexico during the summer months. Because Mexico is comprised of five major climactic areas and dozens of minor ones, explaining summer weather takes more than a paragraph or two.

During balmy winter month's mainland Mexico weather arrives predominantly from the north and west. The upper-half of the Baja California peninsula is fully involved with weather patterns that also affect southern California. During the summer, northwest influences die down a great deal and a lot of weather originates over northern Mexico, especially in the southern half of the peninsula. A typical summer day can see daytime highs in Ensenada at 75F but to the east on the shore of the Gulf of California it can be a blistering 120F. The heat moderates just a little as one progresses southward along the eastern shore of Baja California. A typical summer day in Mulege or Loreto can be 105F, La Paz 112F and Cabo San Lucas 104F. In August temps tend to recede five or ten degrees but humidity levels all along this coastline average 70% or higher making the heat more uncomfortable. Note: Humidity levels will suddenly drop one day in October.

Along mainland Mexico's northwest coast summer temperatures blaze from June to November. The Sonora state capitol of Hermosillo can roast under 110F temperatures. Guaymas, on the coast, will have perhaps ten degrees lower temps. but humidity will be forty or more points higher (a tropical storm can raise humidity levels).

Mazatlan will be just a few degrees cooler than Guaymas, but then even further south temperatures tend to moderate into the eighties and low nineties, also with fifty to eighty percent humidity. From around San Blas to the Guatemalan border (and beyond of course) humidity levels rarely drop below fifty percent, day or night, summer or winter. Acapulco normally has a daily high that varies maybe eight degrees summer and winter, and a low temperature that is seldom more than ten degrees less than the respective high.

Seashore hi/lo's are much tighter along the coast than they are in the high altitude interior of Mexico. At the Flores de Las Peñas RV Park, summer temperatures rarely venture outside of 84 and 80 respectively. Warm as this may sound, I spent a summer in Mulege, Baja California where every day was above a hundred degrees and at no time for four months did the temperature drop below eighty-eight.

HURRICANES AND TROPICAL STORMS

The Atlantic hurricane season starts about two months earlier than the Pacific hurricane season. All hurricanes get their start in the Atlantic---the Atlantic storms form and pound Mexico's east coast and Yucatan peninsula, and western hurricanes originate from hot moist air arriving in the gulf of Tehuantepec via the narrow Isthmus of Tehuantepec. There is no sure-fire way to predict the birth of a hurricane except to say that at one time in their development they were a tropical storm.

Atlantic hurricanes tend to grow much larger and intense than Pacific hurricanes (more category four and five storms). Atlantic hurricanes tend to be much more off-the-wall in terms of their forecasted track and where they actually end up going. Atlantic hurricanes also tend to end up bashing themselves to death on Mexico's eastern mountain ranges. All of their energy turns to incredible amounts of rainfall---sometimes amounting to more than fifty inches in just a couple of days. It is dangerous to find yourself driving in those mountains if a hurricane is arriving. Find a level parking area away from ravines, cliffs, or structures that may fly apart and crash into your rig.

Pacific hurricanes generally start out in the gulf of Tehuantepec and for the months of June and July spin off westward or northwestward toward Hawaii. As the last week in August approaches for some reason these storms will tend to track more northward and end up paralleling the coast. September can see hurricane after hurricane paralleling the coast. In mid-to-late September these storms will start to curl eastward. A few curl back on themselves and crash into Acapulco, others remain offshore until reaching Puerto Vallarta or above and then hit landfall. Others will keep wobbling northwest and impact the southern half of the Baja peninsula. Late in the season at any unpredictable time one of these storms can suddenly curl east and cut a wide swath over the Baja peninsula. It will end up regaining a bit of strength over the narrow Gulf of California, and then usually the hurricanes will head east or northeast and bash themselves against the western Sierra Madre Mountains. Again, thunderous quantities of rain will gully wash the entire region. I can remember times when rain fell so hard on the flats that it bounced back into the air making an impenetrable shroud that hid the ground and everything less than three feet tall! This would make for absolutely unbearable driving conditions.

The Internet provides one of the best tools to monitor tropical weather. If I were in the gulf coast or Yucatan coastline and determined that a tropical storm was headed toward me I wouldn't wait around to see if it developed into a full-blown hurricane. It's safer to move inland a hundred miles and eliminate the possibility of getting caught in a storm surge or coastal flooding.

Tropical Storms can develop anywhere in Mexico in the summer but mostly they originate or stick-to oceans and shorelines. These storms can range in intensity from moderate to incredibly violent so don't sell them short just because they aren't classified as being a hurricane.

Thunderstorms are common especially where mountains are close to the sea. The best way I know of to detect an approaching or nearby thunderstorm is to switch on an AM radio and wait for the blast of static announcing a bolt of lightning. I unplug my rig from shore power during storm activity because sagging transmission lines that touch each other or a lightning strike on a conductor can really send bad glitches of power throughout the system. Generally speaking most thunderstorms in Mexico migrate east to west---meaning they come ashore from the Gulf of Mexico and roll out to sea on the Pacific coast.

Hurricanes, tropical storms and thunderstorms have one thing in common---they all have monumental up and downdrafts. The downdrafts are especially noticeable. They can bring air that is a full forty degrees cooler. Many hurricanes leave a pool of seventy-five degree air in place of hundred-degree air for one or two days after they pass. Mexicans, sleep-deprived because of hot and humid nights, frequently snooze right after a storm has passed (and you thought it was because of typical Mexican nonchalance).

SUMMER PARADISE AT HIGH ALTITUDES?

Temperatures are definitely cooler the higher up you go---but there's a catch and that is humidity. In the region where I live, I occasionally "escape" the heat by driving two hundreds miles to 7,000 ft. from my beach digs. Instead of eighty-six the temperature may be somewhere in the mid-seventies. The humidity at altitude goes up and down summer and winter, but many times in the summer it will raise to above sixty percent and even seventy-five degrees will start to feel clammy. In the central interior San Miguel de Allende may bask in eighty-five degrees but the humidity may be but thirty-percent. The rule is, don't take online weather forecasts too seriously as most of the services omit humidity levels, and none do justice to Mexico's thousands of microclimates.

BAYS BLOCK COOLING BREEZES

An ideal anchorage for vessels is a sheltered bay. But a sheltered bay in the summer is less comfortable for three reasons: The first is those "sheltering hills around the bay" block breezes. No swells and waves allow the water to heat up and perspire more moisture into the air, and lastly, bugs just love all of it. Bays can be like the Black Hole of Calcutta, while outside on beaches open to the waves and breezes things can be downright comfortable (until the breeze quits that is).

AVOIDING BUGS

The best way to avoid mosquitoes, and no-see-ums is to camp no less than two miles from the nearest marsh, lagoon, or river. The second point is when occasional big waves leave seawater puddles on the sand, prepare for a sudden hatch of biting insects.

NOW FOR ALL THE GOOD STUFF!

July and August are the peak vacation period for Mexican tourists (especially the beaches). Mazatlan, Puerto Vallarta, Barra de Navidad and Acapulco hotels will be full but mostly the RV parks will be almost deserted. The same goes for interior Mexico RV parks: You can get the space that you wish. Restaurants that are jammed packed with tourists in the winter will be wide open. Beach restaurants can get a little crowded in summer "high season" but they are still manageable.

Winter mornings at high altitude (Patzcuaro, San Cristobal de Las Casas, Toluca, Zacatecas), can be downright frosty with temps in the thirties. These areas are much balmier in the summer when overnight temps can dip into the (delicious!) sixties.

From the middle of the Baja peninsula to the tip the best weather can be found from late March to June, and late October to December. Pesky northern winds are replaced gradually by warm and moist southern breezes. On a whole however, the coolest summer weather is found from the border down to El Rosario on the Pacific coast.

If you are planning on descending into the Copper Canyon in the winter, you may wish to know that on top, say at the small town of Creel, snow may coast the ground, while a mile straight down, temperatures support citrus and mango fruit. On the other hand in high summer the narrow canyon can be a veritable broiler. On top at Creel temps may just reach into the seventies. March and November make great compromise months to visit both.

IN MOST OF MEXICO SUMMER IS BY FAR THE MOST BEAUTIFUL SEASON

Everything is much greener and because much of Mexico is brown this can make all the difference in the world appearance-wise. Flowers bloom, mangoes ripen and the country seems to be much more lush and verdant.

One of my favorite activities in the summer is to relax beneath a patio or awning roof and enjoy heat lightning in the evening. The rich scent of rain wafts its way through and flowers seem to be especially fragrant. Picking purple finger-size bananas in a tropical drizzle is another of my favorites.

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