Guatemala [1] has a tropical climate, though temperatures vary greatly between regions because of differences in altitude. The coastal plains and lowlands have an average yearly temperature of about 27°C (80°F), with little seasonal change. Mountain valleys 1,200–1,800 meters (4,000–6,000 feet) high are usually comfortably mild. Major cities such as Guatemala City [2], Antigua [3], and Quetzaltenango [4] all lie at these altitudes, meaning they have mostly pleasant year-round springlike temperatures of 16°C–21°C (60°F–70°F).
Higher mountain peaks and valleys sometimes have frost and average 4°C (40°F). Keep in mind that these are averages and certain times of year are markedly warmer than others. The North American winter solstice often brings the arrival of cold fronts, which make temperatures in the highlands dip below freezing on mountain summits but also in highland cities such as Quetzaltenango.
If you’re traveling to Guatemala November–February, bring a warm sweater or two for the chilly highlands and a heavy jacket if you plan to climb some volcanoes. At the other extreme, March and April, coinciding with the spring equinox, is the warmest time of year. Temperatures in the Petén [5] lowlands, Izabal [6], and the Pacific Coast [7] plain routinely hover around 38°C (100°F) during these months. Guatemala City and Antigua hover at around 29°C (85°F).
There are distinct dry and rainy seasons in Guatemala. The dry season runs from November to the beginning of May. If you are a photographer interested in capturing images of Guatemala’s fantastic mountain scenery, you may want to avoid visiting during March and April, when haze from dust and agricultural burning tends to obliterate any views of surrounding scenery. The volcanoes around Antigua and Lake Atitlán become extremely difficult to spot during this time of year.
The rainy season generally lasts May–November with daily showers during most of this period, usually in the afternoon. Mornings are usually sunny and clear, with a gradual buildup of giant rain clouds throughout the day, culminating in a torrential downpour. The latter months tend to be the rainiest with deluges sometimes lasting entire days. The rainy season is sometimes referred to as invierno, meaning winter, though it is officially summer in the Northern Hemisphere, where Guatemala lies. Verano, or summer, refers to the tail end of the dry season.
The Pacific Coastal plain and the Western Highlands [8] receive 76–150 centimeters (30–60 inches) of rain a year, and the Eastern Highlands average 51–76 centimeters (20–30 inches). Again, these figures will vary greatly from place to place depending on factors such as altitude and what side of the mountain chain you’re on. Petén receives 200–381 centimeters (80–150 inches) of rain annually, which falls throughout most of the year.
The rainiest place in Guatemala is said to be the Cerro San Gil rainforest [9], on the Caribbean Coast, where warm, moist air rises from the ocean and dumps precipitation on this small mountain chain. There is really no dry season to speak of in this area.
There are sometimes breaks in the rainfall, known as canícula, for a week or two in July and/or August. Rainfall can vary substantially from year to year, which is due to factors such as the presence of El Niño or La Niña. El Niño often means a prolonged dry season, which can lead to intense wildfires in forested areas such as Petén.
Hurricanes and tropical storms sometimes hit Guatemala during the latter months of the rainy season, causing widespread damage. Much of this is due to soil saturation on deforested and waterlogged hillsides, which give way to devastating mudslides, as occurred in parts of the Lake Atitlán basin after Hurricane Stan in 2005. Hurricane Mitch also left a trail of devastation along the Caribbean Coast in 1998, obliterating much of the banana harvest and destroying thousands of homes.
Links:
[1] http://www.moon.com/destinations/guatemala
[2] http://www.moon.com/destinations/guatemala/guatemala-city
[3] http://www.moon.com/destinations/guatemala/antigua
[4] http://www.moon.com/destinations/guatemala/the-western-highlands/quetzaltenango
[5] http://www.moon.com/destinations/guatemala/peten
[6] http://www.moon.com/destinations/guatemala/el-oriente-and-izabal
[7] http://www.moon.com/destinations/guatemala/the-pacific-coast
[8] http://www.moon.com/destinations/guatemala/the-western-highlands
[9] http://www.moon.com/destinations/guatemala/el-oriente-and-izabal/puerto-barrios/puerto-santo-tomas-de-castilla/cerro-san-gil-and-rio-las-escobas