🇵🇷Puerto Rico

Puerto Rico sits at approximately 18°N in the Caribbean Sea as an unincorporated US territory (9,104 km²) comprising the main island of Puerto Rico, Vieques, Culebra, Mona, and numerous smaller islands and cays. The terrain features the rugged Cordillera Central mountain range rising to Cerro de Punta (1,338 m, the highest peak), narrow coastal plains along the Atlantic (north) and Caribbean (south) shores, El Yunque National Forest — the only tropical rainforest in the US National Forest System receiving up to 4,000 mm annually in its montane cloud forests — and extensive mangrove and coral reef ecosystems surrounding the islands.

This geography produces a tropical maritime climate (Af/Am Köppen) characterized by warm temperatures year-round, high humidity, abundant rainfall especially on windward northern and eastern slopes, and vulnerability to Atlantic hurricane season from June through November.

San Juan averages 25°C in January and 28°C in July with 1,500 mm rainfall concentrated May–November. Ponce (south coast rain shadow) registers 24°C in January and 28°C in July with 950 mm — drier with distinct wet and dry seasons. Mayagüez averages 25°C in January and 28°C in July with 1,750 mm. El Yunque peaks receive over 4,000 mm making it one of the wettest locations in the Caribbean.

Puerto Rico endured severe Hurricane María (20 September 2017, Category 4-5, 2,975–3,000+ deaths, $90 billion damage — the deadliest Atlantic hurricane since Mitch 1998, severe the power grid and causing months-long blackouts across the island), Hurricane Fiona (18 September 2022, massive flooding and island-wide power failure), Hurricane Irma (September 2017, grazing the northeast as Category 5), the severe 2014–2016 ENSO-linked drought stressing agriculture and water supplies, accelerating sea-level rise threatening Old San Juan UNESCO World Heritage fortifications and coastal infrastructure (up to 1 m by 2100 projected), the severe 2024 Caribbean marine heatwave (ocean temperatures exceeding 31°C, causing severe coral bleaching across Puerto Rican reefs), and increasing extreme rainfall intensity linked to warmer Atlantic sea surface temperatures.

Our archive covers 4 Puerto Rican cities with daily ERA5 reanalysis data going back to 1940. The warmest July averages occur in Bayamón, around 30.2°C, while Bayamón records the coldest January nights near 22.5°C. Comparing the last decade against the 1940–1970 baseline, mean temperatures across these cities have risen by about 1.1°C.