By David Cannon and Amanda Delaney – Weather Routing Inc.
Ah the Pacific Coast of Central America and Mexico. The many resort destinations conjure up images of surf, sun, sand, and warm temperatures, just the right remedy for those looking to escape winter’s icy grip in more northern climates. But with the sun and fun, there can’t possibly be any weather dangers to worry about along the way … can there? Well, as we move into the latter part of winter, the weather is not quite as volatile as earlier in the season, but we have concerns nevertheless…
… With this in mind, let’s take a look at what Mother Nature typically offers from the Baja Coast to Central America. Everything from cold fronts and the higher winds and large waves they can bring to the tropics (yes, the tropics) will be covered in this article. There’s a lot to cover, so let’s have a look.
Central America to southern Mexico:
During the winter months, most regions along the Western Coast of Central America and along Southern Mexico have benign weather conditions as these regions experience their dry season. In most cases, winds are generally light of (Beaufort) force 3 or less and swells offshore Central America are typically from the south to southwest of 3-6ft. Even along the immediate coast, the winds will be typically onshore by day force 2-3 and offshore by night force 2 or less. However, there are some hazards to be aware of in certain areas prone to “funneling” or “channeling” of higher north to northeast winds during this time of year.
During February and Early March, strong highs build over the Central United States and cold air dives southward from the Gulf of Mexico over Southern Mexico and Central America. The cold air funnels through gulfs and valleys through Southern Mexico and Central America resulting in enhanced northerly or northeast-easterly (depending on how the valley or gulf is oriented) winds. The enhanced northerly winds reach the Gulf of Tehauntepec approximately 18-24 hours after strengthening over Southern Texas. From there, winds will increase about 24 hours later over much of Central America before strengthening over the Gulf of Panama about another day later.
During these events along the Western Coast of Central America, winds increase from the north of force 5-6 through the Gulf of Panama and swells build from the north of 8-10ft at the mouth of the gulf. Winds can wrap around the Azuero Peninsula with winds increasing to northeast to east of force 4-5 and swells building more east to northeast of 4-7ft, due to the more east to west orientation of the coastline on the south side of the peninsula.
Other areas prone to the funneling northeast winds are through the Gulfs of Papagayo, Dulce, Nicoya and Fonseca. Here winds will increase to force 5-6 through the gulfs but, during stronger surges, winds can locally increase up to gale force through these gulfs. Swells will build northeast to east of 6-9ft offshore of these gulfs, though higher sets of 10-11ft are possible especially offshore the Gulf of Papagayo.
Typically, the strongest surges of northerly winds can be found in the Gulf of Tehauntepec located in Southern Mexico. These northerly winds, known as Tehuantepecers, can reach gale to storm force and generate northerly swells in the southern gulf as high as 12-18ft. The strongest surges typically occur in January through Early February and will last about 4-5 days. By Late February and Early March, the air moderates while diving southward over the western Gulf of Mexico and over the Gulf of Tehuantepec. Therefore, the northerly winds will be weaker than during the heart of the winter months. However, gale force winds are likely though storm force conditions become less frequent. The duration of these higher winds last approximately 2-4 days due to more frequent cold fronts moving across the Western Gulf of Mexico that weaken the ridge of high pressure over Southern Mexico.
During Late March through May, the enhanced north and northeast winds that funnel through the gulfs and valleys in Southern Mexico and Central America gradually become weaker and less frequent as any cold air that funnels through these regions continues to moderate more readily and more rapidly through the spring. However the interaction of the thermal trough that remains stationary along the Colombian coast year round and any high pressure ridges over the Western Caribbean Sea will allow northerly winds to funnel through the Gulf of Panama. Winds over the Gulf of Panama become north and northeast of force 4-5 and swells in the southern gulf become northerly of 5-7ft.
Farther north, the Gulf of Papagayo generally maintains similar winds of northeast to east force 4-6 and swells of northeast to east of 5-8ft offshore the gulf. However, winds lower over the gulfs of Fonseca, Dulce and Nicoya during the spring. In these regions, winds are generally north to northeast of force 4-5 and swells offshore these gulfs become north to northeast 4-7ft.
Across the Gulf of Tehuantepec, any northerly wind events during the spring will lower to mainly force 6-8, with the highest conditions occurring in March. The associated swells offshore the southern gulf become northerly of up to 10-14ft. These northerly surges become less frequent during the spring and last approximately 2-3 days.
During Late April and May, the equatorial trough begins to migrate farther north between the Equator and 10N and from Colombia westward over the Eastern Pacific Ocean. Showers and thunderstorms move east to west along this trough and define its location on satellite imagery. The arrival of the trough marks the beginning of the rainy season for Panama and Costa Rica as showers and thunderstorms move westward across these countries and track westward over the open waters of the Eastern Pacific Ocean.
For most of the period, the tropics really are not much of a concern at all. Tropical cyclone development during late winter almost never occurs, and even by late April is quite rare. Tropical cyclone season in this part of the world does not officially begin until 15 May, with development during May occurring on average about once every other year. Any development at all will generally be found in the waters offshore the Central American coast, with dominant tracks toward the west. These systems typically develop south of Central America and the Mexican Riviera and move toward cooler waters west of 105W-110W, where weakening and eventual dissipation occurs.
A secondary, less likely track for tropical cyclones allows for more of a “re-curvature” of such systems, taking them closer to and into the Mexican Riviera, the Sea of Cortez, and the southern Baja. However, cold fronts and associated weather features in the upper levels of the atmosphere are typically not large and strong enough to effectively “pick up” tropical cyclones and allow for this re-curvature in track to occur. This is more likely to occur during mid to late summer, when we are normally just past the peak period for tropical activity in this region.
The Mexican Riviera and Baja California:
Tranquil weather can be found along the Mexican Riviera during the winter and spring. Winds in more offshore waters are generally from the west to northwest of force 3-4 and swells are from the west to northwest of 4-7ft. Winds are typically onshore by day of force 2-4 and offshore by night force 3 or less along the immediate coast. During the winter months, larger northwest swells will propagate southeast from the Northern Pacific Ocean of up to 8-9ft, however these swells are generally long in period of 15-20 seconds apart.
Farther north, a thermal trough of low pressure generally resides over the Sea of Cortez and extends northward along the Gulf of California. Winds over the Sea of Cortez and Gulf of California are north to northwest of force 2-4 and swells are north to northwest of 2-5ft. This trough will shift eastward when cold fronts move over California or a ridge of high pressure builds over Baja California. Ahead of cold fronts, winds over the Gulf of California will ease and become south to southeast of force 2-4 and swells become south to southeast of 2-4ft. Over the Sea of Cortez, the winds will remain N-NW force 2-4 and swells north to northwest of 3-5ft.
Behind cold fronts, as strong ridging builds over Northern Mexico, winds will increase north to northwest of force 4-6 and swells build north to northwest of 4-7ft in the Gulf of California and 7-9ft in the Sea of Cortez. During February though, north to northwest winds will increase up to force 7-8 in the Gulf of California and become force 5-7 in the Sea of Cortez. Swells during that time will build from the northwest of 6-9ft in the Gulf of California and northwest 9-12ft in the Sea of Cortez.
The trough will shift westward over Baja California when a strong high builds over the Southwestern United States. During these times, the winds will lower to northwest force 2-3 over the Gulf of California and Sea of Cortez with swells lowering to northwest 1-3ft in the Gulf of California and 2-4ft in the Sea of Cortez. However, abeam any southwest to northeast oriented valleys, winds can increase to force 5-7 in the northern Gulf of California which is very similar to Santa Ana winds over Southern California.
A unique weather feature that occurs over Southern Baja California during the spring is the Coromuel winds in La Paz Bay. This wind event develops when cool Pacific air is drawn across the southern Baja peninsula to the Gulf of California. The onset of these offshore (southwest) winds occurs during the late afternoon/early evening hours and can rapidly increase during the overnight hours over La Paz Bay. The winds usually abate during the morning hours. These events also allow westerly winds to “wrap” around the southern Baja coast where winds will locally increase up to force 5-6.
During February and Early March along the Western Baja California Coast, winds are generally north to northwest of force 4-6 and swells are typically north to northwest 5-9ft. The strength of the winds is determined by the interaction of a ridge of high pressure over the Eastern Pacific Ocean and the thermal trough of low pressure over the Gulf of California. However, when cold fronts approach the California Coast, the winds will lower and become more west to northwest of force 2-4 and swells become west to northwest of 4-7ft. Once the cold front tracks through California and Northern Baja California, the winds can increase to force 5-7 and swells will build from the north to northwest of 8-12ft.
The cold fronts become less frequent and retreat farther north over Northern California during the spring. Winds become north to northwest force 3-5 and swells north to northwest of 4-7ft. However, there are times that winds will increase up to force 5-6 along capes and headlands during the afternoon hours and swells will locally build up to 6-9ft offshore these regions. These higher wind events usually occur when the ridge of high pressure over the Eastern Pacific Ocean strengthens along the Western Coast of Baja California and interacts with the thermal trough over the Gulf of California.
Tying it All Together: Some Concluding Remarks
So now that we’ve covered the typical weather patterns, what does it all mean? Well even though we’re past winter’s volatility for the most part, that doesn’t mean we’re completely out of the woods when it comes to wind surges, especially farther north across the northern Baja and in gulfs along Mexico and Central America. Thankfully, though, adverse weather conditions tend to be confined to a much smaller area, and are far less frequent and prolonged, especially as we proceed farther into spring, when cold fronts are virtually a non-issue and non-existent…
… and lest we forget the tropics. Fortunately, we’re only moving into the very beginning of tropical cyclone season, and frequency of tropical development pales in comparison to what is normally seen later in the season, but we’ll need to keep a close eye for any developments as the season gets underway.
So to sum it all up, getting from point A to point B will be easier this time year, but not without its potential ”roadblocks” along the way. Stay safe, stay alert, and keep abreast of the situation. The ever watchful eyes of trained professional meteorologists can prove to be a valuable asset in keeping you ahead of the game, no matter what Mother Nature has in store for you.
Safe travels to all.
Did you find this article useful? Read Major Wind Events across the Mediterranean during the Spring and Summer by David Cannon of WRI.
David Cannon is a Director of Yacht Operations/Senior Meteorologist and Racing & Tournament Specialist, and Amanda Delaney is a Senior Meteorologist. Both are employed at Weather Routing Inc. (WRI), which has provided weather route/forecast information and meteorological consultations to mariners since 1961.
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