September Weather in Saipan, Northern Mariana Islands

Last updated: August 31, 2025

In September, Saipan, Northern Mariana Islands, experiences a tropical climate characterized by warm temperatures and high humidity. The maximum temperature reaches around 30°C (86°F), while the average hovers at 28°C (82°F), ensuring a comfortable yet warm environment. Nighttime brings slightly cooler conditions, with a minimum of 25°C (78°F). However, visitors should be prepared for the rainy season, as precipitation amounts soar to 320 mm (12.6 in) across approximately 28 days of the month, resulting in a lush landscape. The island's humidity remains high at 81%, adding to the tropical ambiance that defines this beautiful destination during September.

September Temperature in Saipan

September in Saipan, Northern Mariana Islands, offers a delightful blend of warmth as the summer season begins to fade. With minimum temperatures hovering around 25°C (78°F) and daytime highs reaching up to 30°C (86°F), the island maintains an inviting tropical climate. The average temperature remains steady at 28°C (82°F), mirroring the warm conditions of the preceding months. This consistency highlights Saipan's tropical charm, where the heat persists but is often tempered by gentle sea breezes and occasional rain, creating an ideal atmosphere for beachgoers and outdoor enthusiasts alike. As the island transitions into autumn, the temperatures subtly signal the change while still embracing the warmth of summer.

September Weather in Saipan: Daily Temperature Highs, Lows, and Averages

The chart illustrates September temperature patterns in Saipan, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Saipan, September typically has an average temperature of {2}°C ({3}°F), with highs reaching up to {4}°C ({5}°F) and lows dropping to around {6}°C ({7}°F).
JanFebMarAprMayJunJulAugSepOctNovDec808080818282828282828281
Data source: Temperature data for Saipan generated using information from the Copernicus Climate Change Service.
Choose your preferred temperature unit
The average of daily temperatures (24 hours) calculated across all days in the month.

September Precipitation in Saipan

In September, Saipan experiences significant rainfall, with precipitation reaching 320 mm (12.6 in) over 28 days. This marks a decrease from the record-breaking 409 mm (16.1 in) in August but still contributes to one of the wettest months of the year. The trend of increased precipitation is notable, especially during the summer months, as July and August also showcase hefty rainfall totals, reaching 265 mm (10.4 in) and 409 mm (16.1 in), respectively. As the island transitions into October, the precipitation remains substantial at 365 mm (14.4 in), suggesting that the rainy season continues to hold its grip on the archipelago. This pattern highlights the tropical climate of Saipan, where moisture-laden spells can deeply influence both the landscape and local lifestyle.

September Precipitation Trends in Saipan

The chart displays monthly precipitation patterns in Saipan, with values for each month alongside September’s data, which is highlighted for easy comparison. It shows the amount of precipitation, providing insights into how September’s conditions compare to those of other months. In Saipan, September typically receives around {2} mm ({3} inches) of precipitation spread over approximately {4} days.
JanFebMarAprMayJunJulAugSepOctNovDec525741635912026540932036514174
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
Choose your preferred precipitation unit

September Humidity in Saipan

In September, the humidity in Saipan, Northern Mariana Islands, hovers around 81%, marking a slight dip from the peak summer months of July and August, which both recorded 80% humidity. This trend of reduced humidity reflects a subtle transition into the drier months, while still remaining relatively high compared to the annual average. Overall, the humidity remains consistently elevated throughout the year, fluctuating between 80% and 84%, creating an ever-present tropical ambiance that characterizes Saipan's climate. Interestingly, the humidity begins to rise again in October, hinting at the impending return to more humid conditions as the year progresses.

September Average Humidity in Saipan

This chart illustrates the average monthly humidity levels in Saipan, with September’s data highlighted for easy comparison. It shows the fluctuation in humidity throughout the year, helping you understand how conditions vary by season. In September, average humidity in Saipan is approximately {2}%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec83%81%83%83%84%82%80%80%81%81%82%83%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Saipan

As summer transitions into fall, September in Saipan, Northern Mariana Islands, maintains a consistently high UV Index of 14, reflecting the ongoing extreme exposure category that has characterized the preceding months from May through August. With a daunting burn time of just 10 minutes, it's crucial for outdoor enthusiasts to remain vigilant and protect their skin from harmful rays. This trend of elevated UV levels not only underscores the importance of sun safety throughout the year but also highlights the consistent need for protective measures. For more detailed information on this month’s UV trends, check out Saipan UV Index.

Maximum UV Index Levels in Saipan for September

The chart shows the monthly maximum UV Index (UVI) for Saipan in September, representing the highest UV radiation level. The UVI measures the intensity of ultraviolet radiation from the sun, indicating the potential risk of sunburn and UV-related health issues. In September, the maximum UV index in Saipan typically reaches {2}, which falls under the {3} exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec101214151314141414131110
Data source: Saipan September UVI data generated using information from the Copernicus Climate Change Service.

UV Risk Categories

  •  Extreme (11+): Avoid the sun, stay in shade.
  •  Very High (8-10): Limit sun exposure.
  •  High (6-7): Use SPF 30+ and protective clothing.
  •  Moderate (3-5): Midday shade recommended.
  •  Low (0-2): No protection needed.

September Sunshine in Saipan

September in Saipan, Northern Mariana Islands, offers a delightful respite with 264 hours of sunshine, marking it as a month that mirrors the brightness of February. After a sun-drenched May with a peak of 339 hours, the warmer months gradually transition into the milder days of fall. Interestingly, despite the slight decline in sunlight compared to the vibrant summer months, September maintains a pleasant brightness that invites exploration and relaxation. With sunshine hours steadily tapering from the summer peak, this month serves as a gentle reminder that while summer's intensity wanes, the beauty of Saipan remains ever radiant, making it a wonderful time to enjoy the island's stunning landscapes.

Monthly Sunshine Duration in Saipan: September Highlighted

The September sunshine duration represents the total number of hours Saipan experiences direct sunlight during the month of September, excluding cloudy or obstructed periods. This chart compares the sunshine duration of September with the other months of the year.
JanFebMarAprMayJunJulAugSepOctNovDec230h264h322h316h339h322h303h275h264h273h283h288h
Data source: Saipan September Sunshine duration data generated using information from the Copernicus Climate Change Service.

Chance of Sun in Saipan During September

In Saipan, Northern Mariana Islands, September presents a considerable dip in the likelihood of sunshine, with only a 25% chance of clear skies. This marks a significant decrease compared to the sunnier months of March, which boasts a 77% chance, and even June, with a 42% chance. The trend reveals a gradual decline in sunny days as summer fades—August's 14% is a stark precursor to September's modest offering. As we move toward the fall months, cloudy weather becomes more prevalent, with October trailing behind at just a 12% chance of sun. Thus, while Saipan is celebrated for its tropical charm, September's weather may be more suited for those seeking a cozy, overcast escape rather than beachside basking.

Percentage of Sunny Days in September in Saipan

The chart illustrates the percentage of sunny days in Saipan throughout the year, with September highlighted. It highlights the variation in sunshine across each month and provides an overview of the typical frequency of sunny days, offering insights into how often Saipan experiences clear skies throughout the year.
JanFebMarAprMayJunJulAugSepOctNovDec67%59%77%47%49%43%22%14%25%12%59%45%
Data source: Saipan September chance of sun data, generated using information from the Copernicus Climate Change Service.

Daylight Hours in Saipan in September

In September, Saipan enjoys a consistent 12 hours of daylight, mirroring the previous months of June, July, and August. This extended daylight is a hallmark of the tropical climate, allowing residents and visitors to revel in warm, sun-filled days. As the year progresses towards October, the daylight begins to taper off, shifting back to 11 hours in the fall months. Notably, the transition from longer to shorter days creates a rhythm in Saipan's seasonal experience, highlighting how the island’s beautiful landscape basks in sunlight during the summer's peak before embracing the more subdued tones of autumn.

Average Daylight Hours in Saipan for September

The chart illustrates the variation in daylight duration in Saipan throughout the year, with September highlighted. It shows the monthly changes in daylight hours, calculated by summing the hours between sunrise and sunset.
JanFebMarAprMayJunJulAugSepOctNovDec11h 19m11h 37m12h 2m12h 28m12h 49m13h12h 54m12h 36m12h 11m11h 46m11h 24m11h 13m
Data source: Saipan daylight hours, calculated by summing the hours between sunrise and sunset for each day.

September Winds in Saipan

In September, the winds in Saipan, Northern Mariana Islands, gently calm down, with an average speed of 5.5 m/s (12 mph), marking a notable dip from the earlier months. This softening breeze contrasts sharply with the higher gusts of 8.0 m/s (18 mph) witnessed in May, highlighting a transitional shift as summer wanes. While the wind speed remains consistent with the trends observed in October, it appears to herald a cozy transition into the latter part of the year. Interestingly, November picks up the pace again, reviving stronger breezes at 7.4 m/s (16 mph). As the year unfolds, the wind patterns reflect a natural ebb and flow, inviting both tranquility and a spirited return as the seasons change.

Average September Wind Speed in Saipan

The chart displays monthly wind speed patterns in Saipan, with values for each month shown alongside September's data, which is highlighted for easy comparison. It illustrates the average wind speed, offering insights into how September's wind conditions compare to the rest of the year.
JanFebMarAprMayJunJulAugSepOctNovDec7.87.36.94.88.04.36.15.95.5 m/s5.47.47.9
Data source: Saipan September wind data, generated using information from the Copernicus Climate Change Service.

How September Weather in Saipan Compares to Other Months

Weather in Saipan varies notably across the year, with each month offering distinct climate conditions. This page compares September’s weather to other months in Saipan, focusing on differences in temperature, rainfall, humidity, and UV levels.

September weather is characterized by warmer temperatures, with a minimum of 25°C (78°F) and an average of 28°C (82°F), reaching up to a max of 30°C (86°F). However, it also sees significantly higher precipitation, totaling 320 mm (12.6 in) across 28 days, resulting in a humid atmosphere with 81% humidity. In contrast, January remains slightly cooler, with temperatures ranging from a minimum of 24°C (76°F) to a maximum of 28°C (83°F) and an average of 27°C (80°F). While January experiences much lower precipitation at just 52 mm (2.0 in) over 13 days, humidity is slightly higher at 83%. Overall, September is warmer and wetter compared to the cooler and drier weather of January. For more detailed insights, you can check Saipan weather in January.

In September, the weather tends to be warmer, with average temperatures ranging from a minimum of 25°C (78°F) to a maximum of 30°C (86°F). It is also notably wetter, experiencing an average precipitation of 320 mm (12.6 in) over 28 days, resulting in high humidity at 81%. In contrast, February sees somewhat cooler conditions, with average temperatures between 24°C (76°F) and 28°C (83°F) and significantly less rain, with only 57 mm (2.2 in) of precipitation over 17 days. Despite the differences in temperature and rainfall, both months maintain a consistent humidity level of 81%. For more detailed information, visit Saipan weather in February.

In September, temperatures in Saipan are notably warmer, with an average of 28°C (82°F) and a maximum of 30°C (86°F), while March offers slightly cooler conditions with an average of 27°C (80°F) and a maximum of 28°C (83°F). September is characterized by high precipitation, receiving 320 mm (12.6 in) over 28 days, whereas March sees much less rainfall at just 41 mm (1.6 in) over 13 days. Additionally, humidity levels remain similar between the two months, with March slightly higher at 83% compared to September's 81%. For more detailed weather information, you can refer to Saipan weather in March.

In comparing the weather between September and April, both months feature warm temperatures, but September is generally hotter with a higher average of 28°C (82°F) compared to April's 27°C (81°F). Notably, while the minimum temperatures are similar at around 25°C (78°F), September experiences higher maximum temperatures of 30°C (86°F). However, September also brings much more rainfall, with 320 mm (12.6 in) spread over 28 days, in stark contrast to April's relatively dry conditions with only 63 mm (2.5 in) across 16 days. Humidity levels are comparable, with September at 81% and April slightly higher at 83%. For more specific details about Saipan's April weather, you can refer to Saipan weather in April.

When comparing the weather in September and May, both months experience warm temperatures, with September featuring a slightly broader range, with minimums at 25°C (78°F) and maximums reaching up to 30°C (86°F), while May sees consistent temperatures with a minimum of 26°C (78°F) and a maximum of 29°C (85°F). However, September is notably wetter, accumulating 320 mm (12.6 in) of precipitation over 28 days, compared to May's more manageable 59 mm (2.3 in) spread across 20 days. Humidity levels are relatively similar, with September at 81% and May slightly higher at 84%. For a closer look at the specifics of May weather, visit Saipan weather in May.

When comparing the weather in September and June, both months experience similar temperatures, with minimums of 25°C (78°F), average highs around 28-30°C (82-86°F), and maximums peaking at 30°C (86°F). However, September is notably wetter, receiving 320 mm (12.6 in) of precipitation over 28 days, compared to June’s 120 mm (4.7 in) over 21 days. Additionally, humidity levels remain high in both months, at 81% for September and 82% for June, making for a consistently tropical atmosphere throughout the late spring and early fall. For more details, you can check Saipan weather in June.

When comparing the weather in September and July, both months exhibit similar temperature patterns, with July slightly cooler, featuring a minimum temperature of 26°C (79°F) compared to September's 25°C (78°F). The average and maximum temperatures remain consistent at 28°C (82°F) and 30°C (86°F), respectively, for both months. However, September sees a significant increase in precipitation, receiving 320 mm (12.6 in) over 28 days, compared to July's 265 mm (10.4 in) within the same number of days. Humidity levels are also comparable, with September at 81% and July at 80%. For more details on the weather patterns during July, you can visit Saipan weather in July.

In comparing the weather of September and August, we find both months share similar temperature ranges, with minimums of 25°C (78°F), averages of 28°C (82°F), and maximums of 30°C (86°F). However, September experiences less rainfall, with a total precipitation of 320 mm (12.6 in) over 28 days, compared to August's 409 mm (16.1 in) over 29 days. Humidity levels are also slightly higher in September at 81%, compared to August's 80%. For a more detailed look, check out Saipan weather in August.

September and October show some similarities in weather patterns, but notable differences can also be observed. Both months feature an average temperature of 28°C (82°F) with a minimum of 25°C (78°F) in September and 26°C (78°F) in October. However, October experiences a slight decrease in maximum temperature, reaching 30°C (85°F) compared to September's peak of 30°C (86°F). Precipitation increases in October, totaling 365 mm (14.4 in) over 28 days, which is more than September’s 320 mm (12.6 in) for the same duration. Humidity remains consistent at 81% for both months, further contributing to the tropical feel. For more detailed information, you can check Saipan weather in October.

In comparing the weather conditions of September and November, we see subtle variations. September typically experiences warmer temperatures, with a minimum of 25°C (78°F) and a maximum of 30°C (86°F), while November's temperatures are slightly cooler, with its maximum at 29°C (85°F). Additionally, September is characterized by higher precipitation levels at 320 mm (12.6 in) over 28 days, compared to November's 141 mm (5.5 in) across 23 days, indicating a transition to drier conditions. Humidity is quite similar in both months, with September at 81% and November at 82%. For more detailed information about November's weather, visit Saipan weather in November.

In September, the weather is characterized by higher temperatures, with an average of 28°C (82°F) and maximums reaching up to 30°C (86°F). The month also experiences significant rainfall, with about 320 mm (12.6 in) spread over 28 days, resulting in high humidity levels at 81%. In contrast, December offers slightly cooler conditions, with an average temperature of 27°C (82°F) and maximums peaking at 29°C (84°F). Precipitation drops considerably to 74 mm (2.9 in) over just 19 days, contributing to a marginally higher humidity of 83%. For a detailed look at the weather conditions during this month, you can visit Saipan weather in December.

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Conclusion: What to Expect From September Weather in Saipan

As September unfolds in Saipan, it brings a unique blend of warmth and moisture that sets it apart from other months. With average temperatures hovering around 28°C (82°F), the island experiences a noticeable increase in precipitation, with rain falling on nearly every day, leading to a lush landscape. The high humidity at 81% not only adds to the tropical feel but also creates a sultry atmosphere that is ideal for those looking to embrace the island's vibrant natural beauty. While the summer months might offer slightly drier conditions, September's abundant rain nurtures the lush greenery that defines Saipan's charm. For more insights into Saipan's weather patterns, visit Saipan Climate.