Isabela Weather in September
Isabela in September sees very high daytime temperatures of 30°C (86°F) and nighttime lows of 26°C (79°F). With the highest rainfall of the year it is wise to pack an umbrella and expect frequent showers.
Rainfall in Isabela in September
Prepare for intense rain this month, as it marks the peak rainfall period. Having a poncho will keep you dry through the downpours. Typically, you can expect about 17 days of rain this month, with 156 mm (6.1 in) on average. Expect frequent rainfall this month, and not just light drizzle. When it rains, it tends to come down hard.
Temperature in Isabela in September
September in Isabela brings typical temperatures with highs around 30°C (86°F) and lows of 26°C (79°F). The hottest part of the day is usually in the afternoon, so lighter clothing can help you stay comfortable. With overnight lows of 26°C (79°F), evenings and nights remain warm. Light clothing and an open window or fan can help you sleep comfortably.Our weather planner can help you find worldwide destinations with pleasant weather during this period. January, February, March, April and December typically offer the best weather for Isabela.
Check the conditions for any month of the year.
For a detailed overview over the year and the best time to visit Puerto Rico, check out our Isabela's climate page.
Isabela Temperature in September
Min Temperature
26°C (79°F)
Max Temperature
30°C (86°F)
Chance of Rain
57%
Precipitation
156 mm (6.1 in)
Rainy days
17 days
Daily Historical Temperatures
48-year average (1977-2025)
Based on our historical records, temperatures in Isabela typically stay consistent throughout September, with daily highs averaging around 30°C (86°F). Nights are warm, with lows around 24°C (75°F).
Average temperatures in September
Historical weather for Isabela in September
Browse day-by-day weather records for Isabela spanning 51 years. Select any month and year to see actual temperatures, rainfall, and conditions recorded on each day.
Isabela historical weather extremes in September
Based on 26 years of weather observations (1999-2025), these are the most extreme conditions recorded in Isabela.
- The warmest day in September was on September 29, 2013, with a maximum of 35°C (95°F).
- On September 18, 2022, Isabela saw its coldest September day with temperatures maxing out at 26°C (79°F).
- Isabela registered its coldest September night on September 3, 2024, with temperatures dropping to 21°C (70°F).
Best Places in Puerto Rico in September
Find out more about the weather in Puerto Rico and which places have the best travel conditions in this month. See all of Puerto Rico in September →
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What to Wear in Isabela in September
Warm but pleasant conditions in Isabela in September. Focus on lightweight, maybe with natural fabrics, cotton blend shirts, comfortable shorts, and breathable footwear. A light cover-up for sun protection is smart too. It's going to pour! Pack a good poncho and prepare for very wet conditions.What To Do in Isabela in September
We rated the following activities from 1 (least suitable) to 10 (best) to do.
Check the conditions for any month of the year.
For a detailed overview over the year and the best time to visit Puerto Rico, check out our Isabela's climate page.
See the full Isabela climate overview or explore weather in Puerto Rico.
