September Weather in Puerto Rico

The tables below give the normal September temperatures and rainfall for cities and popular vacation spots in Puerto Rico. There's also information here on hurricanes, plus this month's average humidity and ocean temperature.

The temperature and rain measurements are averages based on weather data collected from 1991 to 2020 for the US National Centers for Environmental Information.

One site, Pico Del Este, is much cooler than others on the list. That's because it's a high mountain peak, at 3448 feet (1050 metres) elevation, in the El Yunque Caribbean National Forest.

Temperature

Average September temperatures in Puerto Rico

High °F	Low °F	Place	High °C	Low °C
89	73	Aguirre	31	23
81	68	Aibonito	27	20
90	70	Caguas	32	21
89	76	Ceiba	32	25
87	73	Dorado	30	23
90	77	Guayama	32	25
87	73	Isabela	31	23
89	72	Juncos	31	22
91	76	La Parguera	33	25
91	70	Lajas	33	21
89	75	Levittown	32	24
87	72	Manati	31	22
80	67	Maricao	27	19
90	72	Mayagüez	32	22
92	72	Mona Island	33	22
72	64	Pico Del Este	22	18
91	69	Ponce	33	20
89	78	San Juan	32	25

Ocean Temperature at San Juan, Puerto Rico averages 83 degrees Fahrenheit (28 degrees Celsius) in September.

Rainfall

Average total precipitation in September. Days are when it rains at least 0.01 inches (0.25 millimetres).

Days	Place	Inches	Milli­metres
10	Aguirre	6.9	174
15	Aibonito	9.4	240
19	Caguas	8.7	221
18	Ceiba	6.4	163
15	Dorado	6.5	165
16	Guayama	7.3	185
16	Isabela	6.7	171
16	Juncos	8.7	222
–	La Parguera	5.5	140
13	Lajas	5.7	144
–	Levittown	8.1	206
14	Manati	5.7	144
–	Maricao	11.6	295
15	Mayagüez	6.6	169
11	Mona Island	4.7	120
12	Ponce	6.9	176
18	San Juan	6.5	165

Relative Humidity at San Juan, Puerto Rico in September averages 79 percent in the morning and 67 percent in the afternoon.

Hurricanes and Tropical Storms

September is the height of hurricane and tropical storm activity for Puerto Rico. All areas of the country could be affected by severe weather.

Overall, the chance of a tropical storm or hurricane getting within 100 miles (165 kilometres) of Puerto Rico this month is 20 percent. There's an eight percent chance of a hurricane and a 1 to 2 percent chance of a major hurricane.