September Weather in Yokosuka, Japan

Last updated: August 21, 2025

In Yokosuka, Japan, September welcomes the transition from summer to autumn with an average temperature of 24°C (76°F), peaking at a comfortable 30°C (85°F) during the day and cooling down to a pleasant 18°C (65°F) at night. This period is characterized by high humidity levels at 86%, creating a tropical feel. However, visitors should be prepared for frequent rain, as the month sees approximately 189 mm (7.4 in) of precipitation spread over 15 days. Embrace the lush landscapes and vibrant atmosphere, while staying mindful of the occasional downpour that enhances the region's beauty.

September Temperature in Yokosuka

In September, Yokosuka, Japan, experiences a delightful transition as summer's warmth begins to wane. With minimum temperatures hovering around 18°C (65°F) and average highs reaching 30°C (85°F), the month offers a perfect blend of warmth and comfort, making it an ideal time for outdoor activities. The average temperature settles at a pleasant 24°C (76°F), inviting residents and visitors alike to relish the lingering summer feel before the cooler autumn air sets in. As the temperatures subtly decline from the peak summer months of July and August, September serves as a gentle reminder of the seasonal shift, providing a refreshing backdrop for exploration and enjoyment in this vibrant coastal city.

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

The chart illustrates September temperature patterns in Yokosuka, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Yokosuka, 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).
JanFebMarAprMayJunJulAugSepOctNovDec464753586671778075686051
Data source: Temperature data for Yokosuka generated using information from the Copernicus Climate Change Service.
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The average of daily temperatures (24 hours) calculated across all days in the month.

September Precipitation in Yokosuka

In September, Yokosuka experiences a significant precipitation level, with 189 mm (7.4 in) of rainfall spread over 15 days. This month marks a continuation of the wet conditions seen in the preceding months, particularly following July's peak of 211 mm. The rainfall in September is higher than August's 117 mm, indicating a return to more consistent wet days. As the transition to autumn begins, the increase in precipitation hints at the approaching heavier rains of October, which historically brings even more moisture. Overall, September serves as a pivotal month in Yokosuka's climatic pattern, bridging late summer warmth with the impending autumn downpours.

September Precipitation Trends in Yokosuka

The chart displays monthly precipitation patterns in Yokosuka, 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 Yokosuka, September typically receives around {2} mm ({3} inches) of precipitation spread over approximately {4} days.
JanFebMarAprMayJunJulAugSepOctNovDec615215512313617521111718927110972
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Yokosuka

As summer's grip loosens, September in Yokosuka, Japan reflects a noticeable shift in humidity, resting at 86%—a slight decline from the sultry July and August, which boasted peak levels of 93% and 90%, respectively. This transitional month marks a gradual move towards the more temperate conditions of autumn, yet still retains a significant level of moisture. Interestingly, September's humidity is higher than the autumn months that follow, such as October at 83% and November at 80%. Overall, the humidity trends in Yokosuka reveal a year characterized by a distinct summer surge, with levels remaining elevated until early fall, before settling into more comfortable ranges as winter approaches.

September Average Humidity in Yokosuka

This chart illustrates the average monthly humidity levels in Yokosuka, 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 Yokosuka is approximately {2}%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec76%74%70%74%82%88%93%90%86%83%80%78%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Yokosuka

As summer fades into autumn, September in Yokosuka, Japan, presents a transition in the UV Index that signals a slight relief from the scorching summer sun. With a UV Index of 10, categorized as very high, residents can expect a burn time of just 15 minutes when exposed to direct sunlight. This marks a decline from the extreme conditions experienced in the previous months of July and August, which maintained a consistent index of 11. While September continues to demand caution, the gradual decrease hints at the approaching cooler months ahead. To stay informed about daily UV levels and ensure safe sun exposure, check the Yokosuka UV Index.

Maximum UV Index Levels in Yokosuka for September

The chart shows the monthly maximum UV Index (UVI) for Yokosuka 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 Yokosuka typically reaches {2}, which falls under the {3} exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec458101111111110754
Data source: Yokosuka 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 Yokosuka

In Yokosuka, Japan, September brings a delightful balance of sunshine, offering 239 hours of daylight to enjoy before the cooler months set in. This month bridges the summer’s peak, where August dazzles with a vibrant 297 hours, and the retreat of daylight in October, which drops to 205 hours. Observing the trends throughout the year, it's clear that as the seasons transition, sunshine hours fluctuate: starting at a modest 187 hours in January, the light steadily increases, peaking in late summer. As we move into fall, the gradual decline in sunshine hours continues, inviting residents and visitors alike to savor the lingering warmth of September’s sun before the autumn chill arrives.

Monthly Sunshine Duration in Yokosuka: September Highlighted

The September sunshine duration represents the total number of hours Yokosuka 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.
JanFebMarAprMayJunJulAugSepOctNovDec187h224h255h269h286h262h249h297h239h205h226h226h
Data source: Yokosuka September Sunshine duration data generated using information from the Copernicus Climate Change Service.

Chance of Sun in Yokosuka During September

In Yokosuka, Japan, September brings a notably lower likelihood of sunny weather, with only a 29% chance of sunshine gracing the region. This trend is part of an overall decline in sunny days as the summer months wane, particularly following the relatively sunnier months of July and August, which see chances of sun hovering around 36% and 39% respectively. As September rolls in, the crispness of autumn begins to take hold, shifting the mood and often the weather patterns. By the time October arrives, the prospects improve slightly to 49%, hinting at a return to brighter days as the season transitions. This variation showcases the dynamic climate Yokosuka experiences, where the transition from summer to fall is marked by a dip in sunny weather.

Percentage of Sunny Days in September in Yokosuka

The chart illustrates the percentage of sunny days in Yokosuka 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 Yokosuka experiences clear skies throughout the year.
JanFebMarAprMayJunJulAugSepOctNovDec52%64%42%50%25%25%36%39%29%49%62%66%
Data source: Yokosuka September chance of sun data, generated using information from the Copernicus Climate Change Service.

Daylight Hours in Yokosuka in September

As summer fades into autumn, September in Yokosuka, Japan offers a gentle transition in daylight duration, with the sun gracing the skies for 12 hours each day. This marks a subtle decline from the lush, long days of August, which boasted 13 hours of brightness. The trend throughout the year reveals a clear seasonal rhythm: January and February begin with a modest 10 hours of daylight, gradually increasing as spring approaches, peaking in May and June with a generous 14 hours. Following this peak, daylight starts to wane, reminding residents that as nature shifts, so too does the light. As autumn settles in, October will usher in a further reduction, leading us towards the deeper shadows of winter, emphasizing the rhythmic dance of daylight that characterizes Yokosuka's yearly cycle.

Average Daylight Hours in Yokosuka for September

The chart illustrates the variation in daylight duration in Yokosuka throughout the year, with September highlighted. It shows the monthly changes in daylight hours, calculated by summing the hours between sunrise and sunset.
JanFebMarAprMayJunJulAugSepOctNovDec10h 3m10h 53m11h 58m13h 4m14h 1m14h 29m14h 15m13h 26m12h 22m11h 15m10h 18m9h 48m
Data source: Yokosuka daylight hours, calculated by summing the hours between sunrise and sunset for each day.

September Winds in Yokosuka

As September settles in Yokosuka, Japan, the city welcomes a gentle breeze with an average wind speed of 5.3 m/s (12 mph), mirroring the conditions of August. This month marks a transition from the lighter winds of summer, which dipped to around 3.5 m/s in July, to a more consistent flow as autumn approaches. Throughout the year, winds tend to oscillate between 3.5 m/s and 6.1 m/s, with a noticeable uptick during the colder months, peaking at 6.1 m/s in February. September's winds reflect a steady rhythm, a hint of the dynamic changes that the upcoming months promise, serving as a prelude to autumn's refreshing embrace.

Average September Wind Speed in Yokosuka

The chart displays monthly wind speed patterns in Yokosuka, 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.
JanFebMarAprMayJunJulAugSepOctNovDec5.46.15.65.55.73.83.55.35.3 m/s5.55.65.8
Data source: Yokosuka September wind data, generated using information from the Copernicus Climate Change Service.

How September Weather in Yokosuka Compares to Other Months

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

September and January present contrasting weather patterns. In September, temperatures range from a mild 18°C (65°F) to a warm 30°C (85°F), with an average of 24°C (76°F), and the humidity is notably high at 86%. This month sees significant rainfall, with about 189 mm (7.4 in) spread over 15 days. Conversely, January experiences much cooler temperatures, where the minimum dips to 0°C (33°F) and the maximum reaches 18°C (64°F), averaging just 8°C (47°F). The precipitation drops to 61 mm (2.4 in) across only 5 days, accompanied by lower humidity at 76%. For more details on Yokosuka’s winter climate, check out Yokosuka weather in January.

September weather is characterized by warm temperatures, with a minimum of 18°C (65°F) and an average of 24°C (76°F), peaking at 30°C (85°F). The month is also quite humid, averaging 86%, and sees significant rainfall, with about 189 mm (7.4 in) over 15 days. In contrast, February experiences much cooler temperatures, with a minimum of 1°C (35°F), an average of 8°C (48°F), and a maximum of 18°C (65°F). Precipitation is significantly lower in February, totaling 52 mm (2.0 in) over just 8 days, and the humidity drops to an average of 74%. For a more detailed look at February conditions, you can refer to Yokosuka weather in February.

September and March present contrasting weather patterns. In September, the average temperature reaches a comfortable 24°C (76°F), with highs peaking at 30°C (85°F), while humidity remains high at 86%. The month also sees a significant amount of rain, totaling 189 mm (7.4 in) over approximately 15 days. In stark contrast, March experiences cooler temperatures, where the average drops to 11°C (53°F), and highs seldom exceed 19°C (66°F). Precipitation is slightly lower at 155 mm (6.1 in) over about 12 days, accompanied by a reduced humidity level of 70%. For more specifics on March weather, you can check Yokosuka weather in March.

Comparing the weather in September and April reveals notable differences in temperature, precipitation, and humidity. September tends to be much warmer, with average temperatures ranging from a minimum of 18°C (65°F) to a maximum of 30°C (85°F), while April is cooler, with temperatures ranging from 6°C (43°F) to 21°C (70°F). Additionally, September experiences heavier rainfall, averaging 189 mm (7.4 in) over 15 days, compared to April's 123 mm (4.8 in) across 10 days. Humidity levels are also higher in September at 86%, compared to 74% in April. For more detailed insights, you can check Yokosuka weather in April.

When comparing the weather in September and May, September typically experiences warmer temperatures, with an average of 24°C (76°F) and maximums reaching up to 30°C (85°F), while May has cooler conditions, with averages around 19°C (66°F) and maximums of 24°C (75°F). Additionally, September tends to be wetter, receiving 189 mm (7.4 in) of precipitation over 15 days, compared to May’s 136 mm (5.3 in) across 11 days. Humidity levels are also slightly higher in September at 86%, compared to 81% in May. For more detailed insights, you can visit Yokosuka weather in May.

In September, the weather tends to be warmer than in June, with average temperatures reaching 24°C (76°F) compared to June's 22°C (71°F). The maximum temperatures in September can climb up to 30°C (85°F), making it hotter than June's peak of 26°C (79°F). However, September also experiences more precipitation, with 189 mm (7.4 in) falling over 15 days, while June sees slightly less with 175 mm (6.9 in) over 12 days. Humidity levels are similar, at 86% in September versus 88% in June. For more detailed information on June weather, check out Yokosuka weather in June.

In comparing the weather of September and July, we see some notable differences and similarities. In July, temperatures range from a minimum of 19°C (67°F) to a maximum of 29°C (85°F), with an average of 25°C (77°F). The month experiences relatively high humidity at 93% and receives approximately 211 mm (8.3 in) of precipitation over 17 days. Meanwhile, September offers a slightly milder temperature range, with a minimum of 18°C (65°F), an average of 24°C (76°F), and a maximum of 30°C (85°F). Although September has lower overall temperatures, it still brings considerable rainfall, totaling 189 mm (7.4 in) spread across 15 days, and maintains high humidity at 86%. For more detailed information on July's weather, you can visit Yokosuka weather in July.

September weather experiences a slight cooling trend compared to August, with average temperatures dropping from 27°C (80°F) in August to 24°C (76°F) in September. While the minimum temperature in September is 18°C (65°F), August starts warmer at a minimum of 21°C (70°F). September also sees an increase in precipitation, totaling 189 mm (7.4 in) over 15 days, compared to 117 mm (4.6 in) during 11 days in August. Humidity remains high in both months, with September at 86% and August slightly higher at 90%. For a closer look at the climate specifics of August, you can check Yokosuka weather in August.

September and October present a noticeable transition in weather conditions. In September, temperatures range from a minimum of 18°C (65°F) to a maximum of 30°C (85°F), with an average of 24°C (76°F) and a high humidity level of 86%. The month sees about 189 mm (7.4 in) of rainfall spread across 15 days. In contrast, October experiences cooler temperatures, with a minimum of 13°C (56°F) and a maximum of 27°C (81°F), averaging at 20°C (68°F). Additionally, October is wetter, accumulating 271 mm (10.7 in) of precipitation over 16 days, while humidity slightly decreases to 83%. For more specific details on the weather in October, visit Yokosuka weather in October.

September and November present notably different weather experiences. In September, temperatures range from a minimum of 18°C (65°F) to a maximum of 30°C (85°F), with an average of 24°C (76°F). The month is characterized by high humidity at 86% and considerable rainfall, totaling 189 mm (7.4 in) over 15 days. In contrast, November sees much cooler temperatures, with a minimum of 6°C (43°F) and a maximum of 22°C (72°F), averaging 16°C (60°F). Rainfall decreases to 108 mm (4.3 in) over 11 days, and humidity drops slightly to 80%. For more detailed insights, check out Yokosuka weather in November.

September and December weather show a dramatic contrast in temperature and precipitation. In September, temperatures range from a mild 18°C (65°F) at night to a warm 30°C (85°F) during the day, accompanied by high humidity levels of 86% and significant rainfall totaling 189 mm (7.4 in) over about 15 days. In contrast, December brings much cooler weather, with temperatures dipping as low as 3°C (37°F) and averaging around 11°C (51°F), while the days can reach up to 21°C (70°F). Precipitation decreases significantly to 71 mm (2.8 in) over just 8 days, with humidity lowering to 78%. For more specifics on December weather, check Yokosuka weather in December.

Compare Yokosuka's Climate with Cities Worldwide

Conclusion: What to Expect From September Weather in Yokosuka

As September unfolds in Yokosuka, the transition from the warm summer months becomes increasingly evident. Temperatures remain comfortably warm but start to dip slightly, providing a refreshing reprieve from the peak heat of August. However, with an average humidity of 86% and frequent rainfall—spreading over 15 days—this month brings an air of moisture that sets it apart. The increased precipitation, totaling 189 mm, contributes to a lush, vibrant landscape, marking a shift into the more temperate autumn season. For those wanting to dive deeper into the climatic nuances of Yokosuka, be sure to explore Yokosuka Climate.