Daylight through the yearLongest day (Jun 21): 13 h 14 min5:48 am – 7:03 pmShortest day (Dec 21): 11 h 1 min6:51 am – 5:53 pm
Sun todaySunrise –Sunset –
ClimateWarmest month September: highs 89°F, lows 78°FColdest month January: highs 83°F, lows 72°F60 in of rain a year, on about 112 dayswettest month NovemberSnow is rare72 days above 90°F, 0 nights below freezing in a typical yearSource: NOAA 1991-2020 Climate Normals, San Juan L M Marin Ap, Pr Rq station, 2 mi away
Earthquakes1,778 of magnitude 3 or more within 50 miles since 197039 of magnitude 4+, 3 of magnitude 5+Largest: magnitude 5.1 on 24 Dec 201014 mi away, near Aguas Buenas, Puerto RicoMost recent: magnitude 3.1 on 20 Sep 202650 mi awaySource: USGS Earthquake Catalog
Natural hazardsOverall risk Insufficient DataSan Juan Municipio, PR, compared with all US countiesSource: FEMA National Risk Index (county level)
Air quality61% of days had good air in 2025209 of 345 days measured136 moderate daysMedian index 45, worst day 99main pollutant: fine particles (PM2.5)Source: US EPA Air Quality Index, nearest monitors: Catano County, PR, 6 mi away
Drinking waterMetropolitanoserves 1,084,637 people from surface water40 health-based violations since 2021latest Feb 2026: surface water treatment, treatment technique13 monitoring or reporting violations since 2021Source: US EPA Safe Drinking Water Information System, largest system serving the town
Elevation53 ft16 m above sea levelSource: USGS 3D Elevation Program
