🇨🇷Costa Rica

Costa Rica lies between about 8° and 11°N as a narrow Central American isthmus straddling the continental divide between the Caribbean and Pacific oceans. The Talamanca range reaches 3,820 m at Cerro Chirripó, and the volcanic cordilleras hold major active stratovolcanoes including Arenal, Poás, Irazú, and Turrialba, producing a steep elevational and rain-shadow gradient.

The humid tropical Af climate dominates the perpetually wet Caribbean slope around Limón and Tortuguero, while the tropical monsoon Am characterizes parts of the Pacific coast such as Quepos. The dry northern Pacific Guanacaste region exhibits tropical savanna Aw conditions, the Central Valley around San José and Heredia enjoys a mild tropical Aw or Am climate, and páramo conditions prevail above 3,000 m on Cerro de la Muerte.

San José at about 1,000–1,300 m has a balmy daily mean of about 20°C year-round with 1,900 mm concentrated in a marked wet season from May through November. Limón on the Caribbean coast receives 3,500 mm with no dry season, while Quepos on the Pacific is warm with over 3,500 mm annually. Liberia in dry Guanacaste has highs of 31–36°C with 1,650 mm and a sharp dry season from December to April.

Cerro Chirripó has frosty conditions with occasional sub-freezing temperatures. The Caribbean trade winds, Pacific ITCZ migration, and the Caribbean low-level jet drive rainfall patterns, including the Veranillo mid-summer drought in July.

ENSO oscillations drive huge interannual swings, with strong El Niño events causing Pacific droughts as in 2015, while tropical storms can bring severe flooding, such as Tropical Storm Nate on the Pacific slope in 2017. Coastal erosion and coral bleaching pose serious threats, and major recent events include the 1991 Limón earthquake-tsunami and recurrent Turrialba ash falls.

Comparing the last decade against the 1940–1970 baseline, mean temperatures across these cities have risen by about 0.9°C.