3 surprising places in the tropics that have had freezes

While we often associate tropical regions with warm and balmy weather, the reality is that even these areas can experience surprising teeth-chattering temperatures under certain conditions.

As the country marches into the cold months of winter, bitter cold, snow, and other wintry precipitation are on the horizon. Wintry weather has already arrived in some places, including in Colorado and northern New Mexico, where a series of storms unloaded several feet of snow, AccuWeather meteorologists reported.

There's the famous, or better yet infamous, polar vortex, a large pocket of very cold air that sits over the planet's poles. A high pressure system can displace this cold air and send it south, usually into the Plains, Midwest and Northeast, leading to bitterly cold winter stretches.

As we head farther south toward the tropics, though, we tend to assume that freezes and colder weather are completely absent, but this isn't always true, even at sea level. In North America, in the winter, the coldest air masses in Canada can bring cold air not just to places like Chicago and New York but all the way to Atlanta and even farther down into the Gulf of Mexico.

Here's a look at three surprising places in the tropics in the United States and worldwide that have seen freezes.

South Florida

As mentioned in AccuWeather's climate rundown of Miami, the Magic City and much of South Florida have a tropical climate. Average high temperatures in Miami are well into the 70s even in the middle of of January. Still, Miami's coldest January low is 45 degrees Fahrenheit on average. And yet, the record low in January is 28 F.

One of these cold snaps happened in January 1977, when an Arctic cold front made its way south into the Florida Peninsula, leading to the first time in recorded history that snow fell in Miami. On the morning of Jan. 19 between 8 a.m. and 9:30 a.m., flakes fell in Broward and Miami-Dade counties. The high temperature that day was only in the 40s, about 30 degrees below the historical average.

One key concept with most cold snaps is the idea of continentality, the degree to which a location is affected by the temperature and moisture characteristics of a large, interior landmass. Key West and the Caribbean islands are more protected from these due to the nearby ocean.

The 1977 cold snap caused more than $300 million in agricultural damage in South Florida, known for its orange groves and other crops. Coral can also be harmed during these cold snaps, as was the case in '77 and more recently in 2010, when hundreds of coral were killed during a January chill.

Southeastern Mexico

Heroica Veracruz, a port city in southeastern Mexico, is about 19 degrees north latitude, firmly in the tropics. Yet, in rare instances, temperatures in the city have dipped into the 30s. Compare that to another tropical savanna climate halfway around the world in Dakar, Senegal, where the temperature has never dropped below 50 degrees.

Remember those high pressure systems that can bring cold air from the north, southward and into tropics? Another phenomenon, called cold air damming, results in a cold air mass being trapped, often on the eastern side of a mountain range, leading to cold air spilling southward.

In the U.S., cold air damming most commonly occurs on the eastern side of the Appalachian Mountains, but it can also happen along the Rocky Mountains and the Cascades in the Northwest, explained AccuWeather Meteorologist Elizabeth Danco. Cold air damming can even impact portions Texas and Mexico when it occurs on the east side of the Sierra Madre, she added.

"Cold air damming events occur due to high pressure moving in from the north and the clockwise circulation around high pressure areas ushering cold air southward into the eastern side of the terrain," Danco said. "The mountains act as a blocking mechanism causing the cold air to get trapped, only being able to move southward on the eastern side of the mountains."

Cold air damming events can last for several days, promoting a stretch of cloudy, dreary and cold weather. In some instances, freezing precipitation, including snow or freezing rain, can also occur when moisture from a nearby storm combines with the trapped cold air.

Cold air damming explains how frigid air has reached places like Heroica Veracruz, well within the tropics.

Sahara Desert

Deserts are known for their high diurnal temperature range, with hot days that can turn surprisingly cold in the winter, including in cities like Phoenix and Las Vegas. The Sahara Desert is another region with significant swings from daytime nighttime temperatures, without the cloud cover and high humidity that moderates this swing.

However, desert cities like Dongola, Sudan, in the Eastern Sahara, occasionally experience temperatures below freezing. The city's record low temperature is 27 F. Cold snaps in this region usually occur when cold air masses from Europe and Asia descend southward.

While we often associate tropical regions with warm and balmy weather, the reality is that even these areas can experience surprising cold snaps under certain conditions. From the historical snowfall in Miami to the rare freezes in southeastern Mexico and the Sahara Desert, these uncharacteristically cold weather highlight the complex interplay of atmospheric phenomena.

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