Cozumel Info, Weather & News

Introduction

Cozumel Island, meaning 'Land of Swallows' (Kosom Lumil in Maya; Isla de las Golodrinas in Spanish) is Mexico's largest island in the Caribbean (third largest overall).  Located 12 miles east of the Yucatan Peninsula, the island boasts an impressive diversity of habitats and species for its size (30 mi long x 10 miles wide).  As the Mexican island with the highest number of endemic taxa, Cozumel is included as a priority biodiversity conservation area (Isla Cozumel Biosphere Reserve, UNESCO, 2016).  The island also forms part of the Mesoamerican Barrier Reef System, the second largest reef in the world. 

The origins of Cozumel are rooted in both tectonic processes and sea level changes.  Based on similarities with the Yucatan Platform and other islands, atolls, and offshore reefs of Belize, some researchers argue Cozumel likely originated as a tectonic block that rifted from the mainland as early as 70 million years ago (Upper Cretaceous); other workers suggest that faulting occurred in more recent times (~5 million years ago).  Seafloor depths surrounding the island range from >400 m (1,440 ft) in the channel between Cozumel and the mainland, to more than 1,200 m (3,900 ft) to the east of the island.  In any case, the oldest rocks exposed on the island date from the early Pliocene (~5 million years ago), and together with the overlying formations, indicate that the island remained submerged from faulted origins until at least 2.5 million years ago.

Digital elevation map of Cozumel.  Click map for link to higher resolution map.  Source:  Wikipedia Commons.

The eastern Yucatan region has been largely tectonically inactive during recent times, so the more recent emergence of the island is likely tied to the ebb-and-flow of Pleistocene glaciations (and the associated sea-level changes) in North America.  The island was exposed briefly about 190-130 thousand years ago (during Illinioan Glaciation) resulting in a layer of caliche on previously formed deposits.  However, sea levels rose ~123 thousand years ago (with the melting of the North American ice sheet during the Sangoman interglacial) and the island again assumed a shallow carbonate reef environment.  It wasn't until 70-14 thousand years ago (Wisconsin Glaciation) that sea levels fell to about -9m (30 feet below present) leading to the formation of ridges of large dunes on the eastern margin of the emerging island (these can be seen on detailed digital elevation maps).  Many of the >190 karst depressions (cenotes) on the island likely owe their formation to this period of emergence.  Also note that this is the earliest time that the plants and animals that we see today could have begun to inhabit the island.  Sea level continued to drop (-130 m) until the peak of the most recent glaciation in North America (~14,000 years ago) and the island began to assume its present-day physiography as the surface of the sea rose to its present level.  The island appears to have been inhabited by Maya beginning by at least the early first millennium AD (Preclassic to Classic periods).

Weather

Weather can be a tricky thing in Cozumel.  Although the daily forecast often shows a chance of precipitation, I rarely cancel plans to go birding unless we are experiencing a "gully-washer" or there are large areas of incoming storms on the weather radar.  In general, it is best to consult the current wind and radar conditions as you plan your activities.

Below are a couple of links to current radar and wind maps, 10-day forecasts, the NOAA tropical storm site, and NOAA Coral Reef Watch.  

A Bit About Seasons in Cozumel

Although Cozumel's weather is somewhat moderated by the surrounding ocean, there are distinct seasonal patterns to the weather:

One can bird in Cozumel year-round without much interference from the weather.  During the wet season, the lagoons tend to have more water (and wildlife), but there are more biting insects and it is generally hotter and more humid; as a result, I tend to get out earlier and spend more time exploring coastal sites that are more open and breezy during that time of year.  During the northern hemisphere winter the island experiences the occasional "Norte"  (Nov - Feb), which bring strong north winds, cooler temperatures, and sometimes precipitation; however one can usually dodge the showers which are often isolated.  And when I do get caught in a passing shower, I just hunker down under a tree until it passes!

Average monthly precipitation (dark gray line) and min (blue)  and max (red) temperatures.  Data axes are in millimeters and centigrade, but data labels are in inches and Farenheit.  (data source:  Wikipedia).

A Few Sources of Information and News