September is close to Hagatna's year-round average, with average highs near 28.6°C and lows around 27.8°C (mean 28.2°C). It is a relatively wet time of year, averaging 250 mm of rainfall and 82% relative humidity across the period.
September is close to Hagatna's year-round average. Across 45 years of records, the warmest September in Hagatna was 2020 — when the month averaged 29°C — while the coldest was 1993 at 27.5°C. Typical September days reach 28.6°C with nights near 27.8°C. The long-term trend is warming, about 0.2°C per decade.
September is a relatively wet time of year in Hagatna, averaging 250 mm of rainfall. The wettest September on record was 2013 with 455 mm, while the driest was 1997 at 72 mm.
Relative humidity in Hagatna during September averages 82%. The most humid September was 2005 at 85%, and the least humid was 1984 at 77%.
September receives about 5.1 kWh/m²/day of solar energy in Hagatna. The sunniest September was 1997 at 6.2 kWh/m²/day, and the cloudiest were 1994 and 2008 at 4.5.
Average wind speed in Hagatna during September is 4.1 m/s. The windiest September was 1994 at 5.4 m/s, while the calmest were 2020 and 2022 at 2.8 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 28.0°C | 28.0°C | 28.2°C | 28.4°C | 28.7°C | +0.7°C |
| Avg High | 28.3°C | 28.4°C | 28.6°C | 28.9°C | 29.1°C | +0.8°C |
| Avg Low | 27.6°C | 27.6°C | 27.8°C | 28.0°C | 28.2°C | +0.6°C |
| Avg Rain | 214 mm | 224 mm | 247 mm | 313 mm | 250 mm | +35 mm |
September temperatures in Hagatna have risen by about 0.6°C between 1981–1985 and 2021–2025.
September has ranged from a record low of 26.1°C (1991) to a record high of 30.4°C (2020).
Rainfall in September is a relatively wet time of year, averaging 250 mm, with a wettest year of 455 mm.
A quieter season to visit Hagatna
If your dates are flexible, the more temperate months of March and February tend to be the most comfortable for visiting Hagatna. That said, September — with days averaging 28.6°C and nights around 27.8°C (mean 28.2°C) and higher rainfall (250 mm) — can still be rewarding for travellers who don't mind the warmth, and often means fewer crowds.
| Year | Avg High | Avg Temp | Avg Low | Hottest Day | Coldest Day | Rainfall | Humidity | Wind | Solar |
|---|---|---|---|---|---|---|---|---|---|
| 2025 | 28.6°C | 28.2°C | 27.8°C | 29.3°C | 27.1°C | 269 mm | 82% | 3.4 m/s | 4.9 |
| 2024 | 29.3°C | 28.9°C | 28.4°C | 30.0°C | 27.5°C | 369 mm | 83% | 4.2 m/s | 4.9 |
| 2023 | 29.3°C | 28.9°C | 28.4°C | 29.9°C | 27.6°C | 196 mm | 82% | 3.7 m/s | 5.3 |
| 2022 | 29.0°C | 28.6°C | 28.1°C | 29.9°C | 26.8°C | 207 mm | 80% | 2.8 m/s | 5.5 |
| 2021 | 28.9°C | 28.5°C | 28.2°C | 29.6°C | 27.5°C | 277 mm | 81% | 3.3 m/s | 5.3 |
| 2020 🔥 | 29.5°C | 29.0°C | 28.4°C | 30.4°C | 26.9°C | 180 mm | 78% | 2.8 m/s | 5.4 |
| 2019 | 28.9°C | 28.4°C | 28.0°C | 29.6°C | 27.0°C | 316 mm | 82% | 3.7 m/s | 4.7 |
| 2018 | 28.5°C | 28.1°C | 27.6°C | 29.3°C | 26.7°C | 344 mm | 82% | 4.2 m/s | 4.9 |
| 2017 | 29.1°C | 28.6°C | 28.0°C | 30.1°C | 26.9°C | 201 mm | 81% | 3.5 m/s | 5.2 |
| 2016 | 28.9°C | 28.5°C | 28.1°C | 29.6°C | 27.4°C | 320 mm | 82% | 3.8 m/s | 4.8 |
| 2015 | 28.9°C | 28.5°C | 28.1°C | 29.5°C | 27.1°C | 194 mm | 82% | 3.9 m/s | 5.4 |
| 2014 | 29.0°C | 28.5°C | 28.1°C | 29.9°C | 27.2°C | 362 mm | 82% | 4 m/s | 4.6 |
| 2013 🌧️ | 29.2°C | 28.8°C | 28.4°C | 29.9°C | 27.3°C | 455 mm | 81% | 4.4 m/s | 4.8 |
| 2012 | 29.0°C | 28.5°C | 28.0°C | 30.0°C | 27.3°C | 315 mm | 81% | 3.5 m/s | 5.2 |
| 2011 | 28.6°C | 28.2°C | 27.7°C | 29.4°C | 27.2°C | 372 mm | 82% | 4.5 m/s | 4.7 |
| 2010 | 28.7°C | 28.3°C | 28.0°C | 29.3°C | 27.3°C | 251 mm | 81% | 4.6 m/s | 5.3 |
| 2009 | 29.0°C | 28.6°C | 28.2°C | 29.9°C | 26.9°C | 290 mm | 84% | 5.3 m/s | 4.6 |
| 2008 | 28.5°C | 28.2°C | 27.8°C | 29.2°C | 27.1°C | 281 mm | 82% | 4 m/s | 4.5 |
| 2007 | 28.5°C | 28.1°C | 27.7°C | 29.4°C | 27.0°C | 311 mm | 83% | 3.8 m/s | 4.8 |
| 2006 | 29.0°C | 28.6°C | 28.3°C | 29.5°C | 27.6°C | 158 mm | 80% | 3.2 m/s | 5.5 |
| 2005 | 28.5°C | 28.1°C | 27.7°C | 29.2°C | 26.7°C | 289 mm | 85% | 4.7 m/s | 4.9 |
| 2004 | 28.1°C | 27.7°C | 27.3°C | 29.8°C | 26.2°C | 163 mm | 83% | 3.6 m/s | 5.7 |
| 2003 | 28.9°C | 28.4°C | 28.0°C | 29.5°C | 27.0°C | 326 mm | 83% | 4 m/s | 4.6 |
| 2002 | 28.8°C | 28.5°C | 28.2°C | 29.9°C | 27.1°C | 256 mm | 82% | 4.3 m/s | 5.5 |
| 2001 | 28.1°C | 27.7°C | 27.3°C | 29.2°C | 26.4°C | 176 mm | 83% | 2.9 m/s | 5.7 |
| 2000 | 28.4°C | 28.0°C | 27.6°C | 29.7°C | 26.3°C | 221 mm | 81% | 4.3 m/s | 5.1 |
| 1999 | 28.4°C | 27.9°C | 27.5°C | 29.4°C | 26.7°C | 256 mm | 82% | 3.9 m/s | 5.1 |
| 1998 | 28.8°C | 28.4°C | 28.0°C | 29.8°C | 26.8°C | 271 mm | 83% | 4.8 m/s | 5 |
| 1997 | 28.6°C | 28.3°C | 27.9°C | 29.6°C | 27.0°C | 72 mm | 81% | 3.7 m/s | 6.2 |
| 1996 | 28.5°C | 28.1°C | 27.7°C | 29.8°C | 26.8°C | 271 mm | 84% | 4.7 m/s | 4.8 |
| 1995 | 28.6°C | 28.2°C | 27.8°C | 29.6°C | 26.4°C | 274 mm | 83% | 4.4 m/s | 4.9 |
| 1994 | 28.6°C | 28.2°C | 27.8°C | 29.5°C | 26.3°C | 272 mm | 83% | 5.4 m/s | 4.5 |
| 1993 ❄️ | 27.9°C | 27.5°C | 27.2°C | 28.9°C | 26.1°C | 167 mm | 84% | 4.2 m/s | 5 |
| 1992 | 28.1°C | 27.8°C | 27.4°C | 28.9°C | 26.5°C | 118 mm | 83% | 5.2 m/s | 5.3 |
| 1991 | 28.0°C | 27.6°C | 27.2°C | 28.9°C | 26.1°C | 273 mm | 84% | 4.5 m/s | 4.6 |
| 1990 | 28.2°C | 27.8°C | 27.5°C | 28.9°C | 26.8°C | 265 mm | 83% | 4.7 m/s | 4.7 |
| 1989 | 28.1°C | 27.7°C | 27.3°C | 28.9°C | 26.3°C | 153 mm | 82% | 4.2 m/s | 5.3 |
| 1988 | 28.5°C | 28.1°C | 27.7°C | 29.9°C | 26.6°C | 115 mm | 81% | 3.8 m/s | 5.3 |
| 1987 | 28.7°C | 28.3°C | 27.9°C | 29.2°C | 26.5°C | 104 mm | 81% | 4.9 m/s | 5.4 |
| 1986 | 28.1°C | 27.7°C | 27.3°C | 28.8°C | 26.5°C | 163 mm | 83% | 4.7 m/s | 5.4 |
| 1985 | 28.1°C | 27.7°C | 27.2°C | 28.9°C | 26.2°C | 310 mm | 82% | 4.4 m/s | 5.2 |
| 1984 | 28.5°C | 28.1°C | 27.7°C | 29.3°C | 26.8°C | 225 mm | 77% | 3.2 m/s | 5.7 |
| 1983 | 28.7°C | 28.3°C | 27.9°C | 29.5°C | 26.3°C | 223 mm | 80% | 4.3 m/s | — |
| 1982 | 27.9°C | 27.6°C | 27.2°C | 28.8°C | 26.4°C | 450 mm | 82% | 4.5 m/s | — |
| 1981 | 28.5°C | 28.1°C | 27.8°C | 29.5°C | 26.9°C | 184 mm | 80% | 4.3 m/s | — |
Actual recorded September data for each year, 1981–2025 — sourced from NASA POWER.
The average high in September is around 28.6°C with lows near 27.8°C (mean 28.2°C), based on 45 years of NASA POWER data.
September averages 250 mm of rainfall in Hagatna, a relatively wet time of year. The wettest on record was 455 mm in 2013.
The hottest September reached 30.4°C in 2020. The coldest dipped to 26.1°C in 1991.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average September temperatures have risen by about 0.6°C. Daytime highs moved from 28.3°C to 29°C and overnight lows from 27.6°C to 28.2°C over the same span.
September is close to Hagatna's year-round average and a relatively wet time of year, so plan for around 28.6°C daytime highs and 27.8°C at night.
Not quite — September is the 7th coolest month in Hagatna, averaging 28.2°C.
For September in Hagatna, pack light layers you can adjust through the day, with typical highs of 28.6°C and lows of 27.8°C. Bring an umbrella or light rain jacket too.
Relative humidity in September averages 82% — quite humid.
Average wind speed in September is 4.1 m/s. The windiest September on record averaged 5.4 m/s (1994).
The wettest September on record was 2013 with 455 mm. On average, September sees 250 mm.
All figures are derived from NASA POWER (Prediction Of Worldwide Energy Resources), based on MERRA-2 satellite reanalysis, covering 1981–2025.
Explore how the weather in Hagatna behaves each September, based on 45 years of NASA POWER climate data from 1981 to 2025. This page breaks down average temperatures, rainfall, humidity, wind and solar radiation for September specifically, along with year-by-year records and how the month has changed over the decades.
