Last updated: August 21, 2025
In September, the weather in the USA and Japan presents a vibrant mix of warmth and moisture. With maximum temperatures reaching 33°C (91°F) and an average of 24°C (76°F), the days are pleasantly warm, while nights cool down to a minimum of 16°C (62°F). This month experiences significant rainfall, accumulating about 173 mm (6.8 in) over 15 days, contributing to an 84% humidity level that enhances the lush beauty of the surroundings. Whether enjoying outdoor activities or exploring urban scenes, September's weather in these two nations offers a dynamic backdrop for unforgettable experiences.
As September rolls in, temperatures in the USA and Japan begin to showcase a delightful transition from summer's swelter to the crispness of autumn. With minimums around 16°C (62°F), and averages peaking at 24°C (76°F), the month offers a comfortable warmth that invites outdoor activities. Notably, highs can reach a sizzling 33°C (91°F), reminding us that summer nuances still linger. Comparatively, Japan experiences similar trends, with temperatures gradually cooling from the summer heights, yet still enjoying balmy days that encourage exploration. This harmonious blend of warmth and approaching autumn chill sets the stage for vibrant fall festivities and breathtaking landscapes, making September a particularly enchanting month for both countries.
As September unfolds, precipitation patterns reveal compelling trends in the USA and Japan. With an average of 173 mm (or 6.8 inches) of rainfall over 15 days, September showcases a notable decline from the intense downpours of July but maintains a robust level of moisture compared to the drier months ahead. Following the peaks of summer, where July recorded a staggering 329 mm (13.0 inches), the steady drop illustrates a transitional phase into autumn. The rainfall in September is part of a broader trend where precipitation levels gradually decrease from May's 156 mm (6.2 inches) through to the early winter months. This change hints at a shift in climate dynamics, as the region braces for cooler, crisper days ahead. Observing these fluctuations helps us understand how weather patterns transform through the seasons, highlighting the delicate balance of nature's cycles.
In September, both the USA and Japan experience a notable shift in humidity, with levels averaging around 84%. This month marks a decline from the peak summer humidity of 92% in July and 91% in August, showcasing the transition towards the drier autumn months. The slight decrease in humidity is a part of a larger trend where values begin to taper off after the summer surge, dropping to approximately 83% in October. Despite this reduction, September remains one of the wetter months, comfortably high compared to the earlier winter months, where humidity dips to about 71% and 75% in the preceding January and February. This seasonal rhythm highlights how September serves as both a bridge and a buffer, as it balances the lingering warmth of summer with the cooler, crisp days ahead.
In September, both the USA and Japan experience a notable continuation of extreme UV Index levels, maintaining an index of 11 and a burn time of just 10 minutes. This trend follows the peak summer months of July and August, when the UV Index even reaches 12. As we transition into autumn, the UV Index starts to decline, but September still calls for caution against sun exposure. This pattern emphasizes the importance of sun safety, as day-to-day activities can still lead to significant UV exposure. For detailed UV Index information, check out Usa UV Index.
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As summer transitions into autumn, September brings a delightful 248 hours of sunshine to both the USA and Japan, reflecting a gradual shift in daylight after the peak summer months. This month’s sunlit hours represent a slight dip from the vibrant August, which boasted 297 hours. However, compared to earlier months, September still shines bright, surpassing the sunshine received in the cooler spring months of March and April. Following the golden glow of summer, this moderate level of sunlight signals the onset of harvest season, inviting locals to enjoy the outdoors while it lasts, before the diminishing rays of autumn pave the way for cozy indoor gatherings. The overall trend highlights a consistent decline in sunshine as the year progresses, yet September holds onto summer's warmth just a little longer, making it a cherished month for outdoor activities and reflections on summer adventures.
As September rolls in, the likelihood of enjoying sunny weather in the USA and Japan presents a mixed but hopeful picture. With a 33% chance of sunshine, September marks a slight increase from the summer months, which saw notably lower probabilities, hitting a low of just 20% in July. This gradual ascent suggests that the transition from the oppressive heat of summer might bring clearer skies. Interestingly, October's 62% chance of sun hints at the promise of even sunnier days just around the corner, making September a bridge between the vibrant warmth of summer and the crisp brilliance of autumn.
As summer fades into autumn, September marks a noticeable shift in daylight duration across the USA and Japan. With an average of 12 hours of sunlight, September serves as a bridge between the long, bright days of summer and the shorter, cozy days of fall. Following the peak of 14 hours in June and July, daylight begins to wane, yet it retains a healthy glow compared to the forthcoming months. This gradual decrease underscores the seasonal transition, inviting a time for reflection and preparation as daylight dips to 11 hours by October. Embracing the changing light becomes an integral part of life, as people savor the warmer days while looking forward to the cozy charm of autumn evenings.
In September, the average wind speed in the USA and Japan dips slightly to 2.4 m/s (5 mph), reflecting a calmness that often embodies the transition into autumn. This month marks a continuation of the downward trend observed from the summer months, where wind speeds peaked in February at 3.6 m/s (8 mph). Comparatively, September's breezes are a gentle whisper after the summer heat, more akin to the subdued winds of June and August, which recorded 2.2 m/s (5 mph) and 2.2 m/s (5 mph) respectively. As the year progresses, we can see a pattern emerging where the wind picks up again toward the end of the year, notably reaching 3.3 m/s (7 mph) in December. This cyclical rhythm of the wind not only adds to the charm of the seasons but also signals a shift in the atmospheric conditions as two vibrant cultures embrace the arrival of fall.
Weather in Usa varies notably across the year, with each month offering distinct climate conditions. This page compares September’s weather to other months in Usa, focusing on differences in temperature, rainfall, humidity, and UV levels.
September and January present starkly contrasting weather patterns. In September, temperatures range from a minimum of 16°C (62°F) to a maximum of 33°C (91°F), with an average of 24°C (76°F), making it warm and relatively humid with 84% humidity. Additionally, this month experiences considerable rainfall, totaling 173 mm (6.8 in) over 15 days. In contrast, January is much cooler, with temperatures ranging from -4°C (25°F) to 16°C (61°F), and an average of 6°C (42°F). Precipitation is significantly lower at 52 mm (2.0 in) over just 6 days and the humidity drops to 75%. For more details, you can check out Usa weather in January.
September and February showcase distinct contrasts in weather. In September, temperatures typically range from a minimum of 16°C (62°F) to a maximum of 33°C (91°F), with an average temperature of 24°C (76°F). This month experiences significant rainfall, with 173 mm (6.8 in) over about 15 days, and humidity levels at a high 84%. In contrast, February is much cooler, with temperatures ranging from a minimum of -4°C (26°F) to a maximum of 20°C (68°F) and an average of just 6°C (44°F). Precipitation is lower at 71 mm (2.8 in) across 10 days, and humidity is also reduced to 71%. For more detailed information about weather trends during this season, visit Usa weather in February.
September and March present contrasting weather patterns, with September typically experiencing much warmer temperatures. In September, temperatures range from a minimum of 16°C (62°F) to a maximum of 33°C (91°F), while March's temperatures are significantly cooler, ranging from 2°C (36°F) to 21°C (71°F). Additionally, September is marked by higher humidity at 84% and greater precipitation, averaging 173 mm (6.8 in) over 15 days, compared to March's 122 mm (4.8 in) over 12 days and a more moderate humidity of 71%. For more detailed information on weather in March, visit Usa weather in March.
When comparing September and April, it's evident that September enjoys warmer temperatures, with averages reaching up to 24°C (76°F) and maximums peaking at 33°C (91°F). In contrast, April experiences cooler conditions, with average temperatures around 15°C (59°F) and highs of only 25°C (78°F). Additionally, September is notably wetter, receiving 173 mm (6.8 in) of precipitation over 15 days, while April has a milder rainfall of 114 mm (4.5 in) spread across just 9 days. Humidity is slightly higher in September at 84%, compared to April's 78%. For more information, visit Usa weather in April.
Comparing the weather in September and May, we see distinct differences in temperature and precipitation patterns. September tends to be warmer, with average temperatures ranging from a minimum of 16°C (62°F) to a maximum of 33°C (91°F), compared to May's cooler average range of 9°C (48°F) to 30°C (86°F). Despite its warmer climate, September experiences more rainfall, with 173 mm (6.8 in) over 15 days, while May receives slightly less precipitation at 156 mm (6.2 in) across 11 days. Interestingly, both months share the same humidity level of 84%, which contributes to a muggy atmosphere typical of transitional seasons. For more details on weather conditions in May, visit Usa weather in May.
September and June exhibit relatively similar weather patterns, though there are distinct differences. In September, temperatures range from a minimum of 16°C (62°F) to a maximum of 33°C (91°F), with an average of 24°C (76°F). In contrast, June has a slightly cooler average temperature of 23°C (74°F), with maximum temperatures reaching 31°C (87°F). Both months experience notable precipitation, with September receiving 173 mm (6.8 inches) over 15 days, while June sees 194 mm (7.6 inches) over 14 days. Humidity levels are also comparable, with September at 84% and June slightly higher at 86%. For more details about June weather, you can visit Usa weather in June.
September's weather is generally milder than July's, with average temperatures ranging from a minimum of 16°C (62°F) to a maximum of 33°C (91°F), compared to July's minimum of 19°C (67°F) and maximum of 34°C (93°F). Humidity is slightly lower in September at 84%, down from July's higher 92%. However, September experiences more rainfall over fewer days, accumulating 173 mm (6.8 in) over 15 days, while July sees a significant 329 mm (13.0 in) over 19 days. For more detailed insights on July weather conditions, visit Usa weather in July.
In comparing the weather between August and September, we can see notable differences in temperature and precipitation. August tends to be warmer, with minimum temperatures around 20°C (68°F) and average highs reaching 35°C (95°F). In contrast, September features cooler averages with minimum temperatures dropping to 16°C (62°F) and maximums peaking at 33°C (91°F). Precipitation is higher in August, totaling 224 mm (8.8 in) over 14 days, compared to September's 173 mm (6.8 in) spread over 15 days. Humidity levels are also slightly elevated in August at 91%, while September averages 84%. For more detailed information, you can visit Usa weather in August.
September and October present a noticeable shift in weather patterns. In September, temperatures range from a minimum of 16°C (62°F) to a maximum of 33°C (91°F), with an average of 24°C (76°F). The month is characterized by significant rainfall, receiving 173 mm (6.8 in) over approximately 15 days, and maintains a high humidity level of 84%. In contrast, October sees cooler temperatures, with a minimum of 10°C (50°F), an average of 19°C (67°F), and a maximum of 29°C (85°F). Rainfall decreases to 138 mm (5.4 in) over only 9 days, while humidity slightly drops to 83%. For more details on weather in October, you can check out Usa weather in October.
September generally experiences warmer temperatures compared to November, with a minimum of 16°C (62°F) and an average high of 33°C (91°F), making it a much hotter month overall. In contrast, November cools down significantly, with temperatures ranging from a minimum of 4°C (40°F) to a maximum of 26°C (79°F), resulting in a much cooler average of 13°C (56°F). Additionally, September is characterized by higher humidity levels at 84% and substantial precipitation of 173 mm (6.8 in) over 15 days, while November sees less rainfall at 47 mm (1.9 in) across just 6 days, along with a slightly lower humidity of 81%. For those looking to understand more about weather conditions during this period, you can check this link: Usa weather in November.
September and December present contrasting weather conditions. In September, temperatures range from a mild 16°C (62°F) to a warm 33°C (91°F), with an average of 24°C (76°F). This month sees quite a bit of rain, accumulating 173 mm (6.8 in) over 15 days, and high humidity at 84%. In stark contrast, December experiences much cooler temperatures, with a minimum of -1°C (31°F), an average of 8°C (46°F), and a maximum of 21°C (71°F). Precipitation drops significantly to 59 mm (2.3 in) over just 8 days, and humidity decreases slightly to 79%. For more details on the December weather, you can visit Usa weather in December.
As September unfolds in the USA, it heralds a distinct transition from the sweltering summer months to the mellow embrace of fall. With average temperatures settling around 24°C (76°F), September offers a welcome respite from the heat, while lingering maximums can still reach up to 33°C (91°F) on warmer days. The humidity remains high, at 84%, adding a touch of stickiness to the air, but the increasing likelihood of rain, with about 15 days seeing precipitation, signals the approaching change in season. This mix of warmth and moisture makes September a unique month, standing out from the drier and more stable weather patterns of summer and the cooler, crisper days of fall. To explore more about the weather trends throughout the year, visit Usa Climate.