Dominican Republic weather in September

Average highs across the country

22.9–33.3°C

Constanza coolest, Punta Rucia / Cayo Arena warmest. No single national average is shown.

Wettest destination

193 mm

Constanza, on about 26 wet days.

Driest destination

63 mm

Cabarete, on about 15 wet days.

• Biggest change ahead: The Southwest moves 29 mm wetter from September into October, while La Romana & Bayahibe moves only 6 mm.
• Punta Cana & the East: September averages 108.2 mm of rain across 5 destinations with records, on about 22.8 wet days. That is 3 mm less than August, and 18 mm below October.
• La Romana & Bayahibe: September averages 111 mm of rain across 2 destinations with records, on about 23.5 wet days. That is 31 mm more than August, and 6 mm above October.
• Santo Domingo & the South: September averages 133.5 mm of rain across 2 destinations with records, on about 19.5 wet days. That is 11 mm more than August, and 9 mm above October.
• Samaná Peninsula: September averages 108.3 mm of rain across 3 destinations with records, on about 23.3 wet days. That is 4 mm less than August, and 13 mm below October.
• North Coast: September averages 78.8 mm of rain across 4 destinations with records, on about 14.8 wet days. That is 31 mm more than August, and 24 mm below October.
• Mountains & the Cibao: September averages 140.3 mm of rain across 3 destinations with records, on about 24.3 wet days. That is 25 mm more than August, and 11 mm above October.
• The Southwest: September averages 107.5 mm of rain across 2 destinations with records, on about 9 wet days. That is 45 mm more than August, and 29 mm below October.

Nothing in this month’s climate table describes seaweed on a beach. Open the sargassum planner and set the month to September — it runs on its own live data layer and its own model version.

Source

Open-Meteo climate reanalysis and Copernicus ERA5-Land reanalysis — open-meteo.com and Copernicus ERA5-Land hourly time series

Baseline

30-year averages, 1995–2024

Climate version

climate-v1.1-1995-2024

• These are 30-year averages, 1995–2024, sampled at each destination's registry coordinates. They are NOT a WMO standard normal, and they are NOT a forecast.
• Celsius, rainfall and wet-day values are transcribed exactly as supplied. Fahrenheit is derived from Celsius, never supplied.
• 17 destinations: monthly values from Open-Meteo climate reanalysis, transcribed as supplied.
• 4 destinations (Jarabacoa, Constanza, Juan Dolio, Punta Rucia): computed by Transekur from Copernicus ERA5-Land hourly reanalysis (CC-BY 4.0), 1995–2024, aggregated over local Santo Domingo calendar days; a wet day is ≥ 1.0 mm.
• Values represent ~9 km reanalysis grid cells: Jarabacoa 19.1,-70.6; Constanza 18.9,-70.7; Juan Dolio 18.5,-69.4 (inland representative cell a few km from the beachfront — the coastal cell is ocean in this dataset); Punta Rucia 19.6,-71.3.
• Mountain grid cells can sit above town centers, so in-town temperatures can run warmer than the grid average. Reanalysis is modeled data, not station observations.
• Wet days for the 17 Open-Meteo destinations are days with measurable precipitation as supplied by that source; that baseline does not define a millimetre threshold, so none is stated for them.