Bayamon Weather in September

September in Bayamon typically sees daytime highs of 31°C (88°F) and nighttime lows of 25°C (77°F). As the wettest month of the year, expect more rainfall than other months.

Rainfall in Bayamon in September

This month brings the peak rainfall of the year, with heavy showers. Be sure to have a poncho ready to manage the downpours. Rain is expected on roughly 18 days, totalling around 155 mm (6.1 in) for the month. Expect frequent rainfall this month, and not just light drizzle. When it rains, it tends to come down hard.

Temperature in Bayamon in September

Daytime highs in Bayamon in September reach 31°C (88°F), with nights around 25°C (77°F). For most visitors, the main thing to prepare for is the heat during the day. Nights stay warm at around 25°C (77°F), so light bedding and good ventilation are worth thinking about.

Sunshine in Bayamon in September

Expect sunny days throughout the month, with an estimated 236 hours of sunshine. This makes it a pleasant time to visit Bayamon.

Wind Speed in Bayamon in September

Wind speeds average 3 m/s (6 knots) during September. At this speed, light breezes keep leaves and small twigs in gentle motion while the wind also provides natural cooling. Since this is an average, some days are more tranquil while others have more persistent light winds that are more noticeable.

Average water temperature in September

With water at 29°C (84°F), conditions are warm and calm. Perfect for those who like tropical water temperatures, though it won't cool you down much.

If you prefer dry days with pleasant temperatures, September may not be the ideal month to visit Bayamon. Our weather planner can help you explore destinations with more pleasant weather conditions.

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Check the conditions for any month of the year.

• January
• February
• March
• April

• May
• June
• July
• August

• September
• October
• November
• December

For a detailed overview over the year and the best time to visit Puerto Rico, check out our Bayamon's climate page.

Bayamon Temperature in September

Min Temperature 25°C (77°F)  

Max Temperature 31°C (88°F)  

Water Temperature 29°C (84°F) *  

Chance of Rain 60%  

Precipitation 155 mm (6.1 in)  

Rainy days 18 days  

Humidity 76% *  

Windspeed 3 m/s (6 knots) *  

Sunshine 236 hours *  

Percentage Sunshine 64% *  

* Data from: San Juan, Puerto Rico (16 KM, 10 Miles).

Daily Historical Temperatures

50-year average (1976-2025)

Based on our historical records, temperatures in Bayamon typically stay consistent throughout September, with daily highs averaging around 31°C (88°F). Nights are warm, with lows around 26°C (79°F).

Average temperatures in September

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Daily Historical Precipitation

50-year average (1976-2025)

Average daily rainfall for each day of the month based on long-term records.

Average precipitation in September

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Historical weather for Bayamon in September

Browse day-by-day weather records for Bayamon spanning 51 years. Select any month and year to see actual temperatures, rainfall, and conditions recorded on each day.

Historical weather Temperatures Precipitation

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Bayamon historical weather extremes in September

Based on 49 years of weather observations (1976-2025), these are the most extreme conditions recorded in Bayamon.

• The warmest day in September was on September 29, 2011, with a maximum of 36°C (97°F).
• The lowest daytime temperature in September was 25°C (77°F), recorded on September 13, 1985.
• The coldest night in September in Bayamon was on September 9, 1988, with a minimum of 21°C (70°F).

What to Wear in Bayamon in September

Warm but pleasant conditions in Bayamon 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. With water temperatures around 29°C (84°F), swimming conditions are excellent. Pack your swimsuit, goggles, and maybe some water shoes. Don't forget sun protection, sunglasses, sunscreen, and a hat. These are all good ideas with this much sunshine.

What To Do in Bayamon in September

We rated the following activities from 1 (least suitable) to 10 (best) to do.

Swimming

8/10

Cycling

7/10

Walking

7/10

Camping

6/10

Outdoor sports

7/10

Select a Month

Check the conditions for any month of the year.

• January
• February
• March
• April

• May
• June
• July
• August

• September
• October
• November
• December

For a detailed overview over the year and the best time to visit Puerto Rico, check out our Bayamon's climate page.

More climate data for Bayamon

Temperature Rainfall Sunshine Humidity Wind Speed Water Temp

See the full Bayamon climate overview or explore weather in Puerto Rico.