Hurricanes and Tornadoes That Hit Guaynabo, PR

The nearest NOAA station with 1991–2020 climate normals is Trujillo Alto 2 SSW, PR RQ, 7 miles southeast of Guaynabo at 115 feet. September is the warmest, with an average high of 90°F and low of 73°F; January is the coolest, at 83°F and 67°F. September is the wettest at 8.5 inches of precipitation on average and February the driest at 3.3 inches; the year adds up to 72.9 inches over 118 days with at least a tenth of an inch. June to November, the hurricane season months, bring 59% of the year's precipitation (43.1 of 72.9 inches); the other six months are drier. September has brought the most of the 65 tropical systems that passed within 75 miles (28); a normal September there has highs of 90°F and 8.5 inches of precipitation. Highs reach 90°F on about 129 days a year, almost all from March to November. A night below freezing comes less than once a year on average. That 72.9 inches is more than at 16 of the 21 Puerto Rico stations used on this site (76%). San Juan, 4 miles northeast, has its own station (San Juan L M Marin Airport, PR RQ): 60.0 inches a year, 12.9 less than here, and a September average high of 89°F against 90°F.

Water temperature at the NOAA tide station San Juan, La Puntilla, San Juan Bay, PR, 6 miles north, averaged 86°F in September and 80°F in February over 2021–2025. Sea level at the San Juan tide gauge, 6 miles from Guaynabo, has risen 0.85 ± 0.06 inches per decade from 1962 to 2025, NOAA's linear trend; at that pace it is 8.5 inches in a hundred years. That is faster than at 45 of the 144 U.S. gauges with a NOAA trend.

Since 1996, the National Weather Service has logged 978 flood, rain, thunderstorm wind and lightning events that began within 10 miles of Guaynabo: 436 flash floods, 402 floods, 76 heavy rain events, 56 thunderstorm wind reports and 8 lightning strikes. They killed 12 people and injured 4, and the NWS estimated $5.76 billion in property and crop damage. The strongest thunderstorm gust on record here was 60 mph, on May 14, 2011. May has had the most flash floods, 87 of 436. Of the 86 Puerto Rico cities on this site with a flash flood on record, 85 have had fewer than Guaynabo.

Flood insurance policyholders in Guaynabo's 5 ZIP codes have filed 213 claims with the National Flood Insurance Program since 1979, and were paid $2.6 million for buildings and contents, in the dollars of each year. The most came from Hurricane Georges in 1998: 26 claims (12% of all) and $45,000, then Hurricane Hortense in 1996 with 20 and Hurricane Maria in 2017 with 18. 36% of the claims carry the name of a storm or flood event; the rest have no event name. Of the 72 Puerto Rico cities on this site with 10 or more claims, 48 have fewer than Guaynabo.