Last updated: February 24, 2025
September in Flagstaff, United States, showcases a dynamic blend of weather patterns, characterized by maximum temperatures soaring to 33°C (91°F) and an average of 17°C (63°F), creating pleasant daytime conditions. However, as the nights fall, temperatures can dip to a cool -1°C (31°F), emphasizing the area’s notable diurnal temperature range. This month experiences 49 mm (1.9 in) of precipitation over the span of 7 days, contributing to the region's lush landscapes. With an average humidity of 59%, visitors can expect a comfortable atmosphere, making September an enjoyable time to explore the natural beauty of Flagstaff.
In September, Flagstaff experiences a refreshing transition as summer gives way to the crispness of autumn. With minimum temperatures dipping to -1°C (31°F) at night, the days remain pleasantly warm, averaging around 17°C (63°F) and reaching a comfortable 33°C (91°F) at their peak. This month stands out as the last hurrah of warmer weather before the chill of fall sets in, making September an ideal time for outdoor activities amidst the breathtaking backdrop of changing leaves. Overall, the temperature trends in Flagstaff reflect a gradual cool-down, inviting residents and visitors alike to embrace the beauty of the season.
In September, Flagstaff experiences a moderate increase in precipitation, measuring 49 mm (1.9 in) over about 7 days. This marks a slight decline from the summer's peak sizzle, particularly evident in July, which recorded a substantial 148 mm (5.8 in) across 16 days. As the city transitions into autumn, September’s rainfall serves as a refreshing bridge, offering a reprieve from the intense summer storms while still contributing to the area's lush landscape. Following a summer of heavy downpours, the precipitation in September reflects a return to more balanced weather patterns, setting the stage for the drier months of October and November. As leaves begin to turn, that modest rainfall ensures Flagstaff remains vibrant and full of life.
In September, Flagstaff experiences a notable shift in humidity levels, peaking at 59%—a refreshing increase compared to the dry heat of summer, where the humidity dipped as low as 33% in July. The transition from the arid conditions of June and July to a more moderate September hints at the impending arrival of autumn, as the humidity begins to climb again towards October's 70%. Overall, this month serves as a bridge, signaling an end to the dry summer and ushering in the moisture-rich months ahead, where humidity levels steadily rise again towards the winter months characterized by significantly higher humidity, reaching 82% in December.
As September rolls into Flagstaff, the UV Index remains notably high at 11, categorizing this period as extreme. Residents and visitors alike should be cautious, as the burn time is a mere 10 minutes. This trend continues from the summer months, where UV levels peaked at 12 and 13, reflecting the region's intense sun exposure. Although the UV Index is slightly lower than in July and August, it still calls for protective measures to be taken seriously. For those enjoying the outdoors, staying informed about UV levels is crucial; you can explore more details at Flagstaff UV Index. As autumn approaches, awareness of UV trends will help ensure a safe and enjoyable experience under the sun.
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As summer gracefully transitions to autumn, September in Flagstaff continues to bask in abundant sunlight, recording an impressive 316 hours of sunshine. This holds strong against the previous months, reflecting a slight dip from the peak summer months of June and July, which boast 375 and 361 hours, respectively. However, September's sunshine remains bright compared to the earlier months of the year, especially showcasing a significant increase from January’s meager 188 hours. This trend not only highlights the tail end of summer but also sets the stage for the cooler fall days ahead, as sunlight hours steadily decline through the coming months. Enjoy the vibrant days of September, capturing the last rays of warmth before the winter chill sets in.
As summer fades, September in Flagstaff emerges with a respectable 67% chance of sunny weather, marking a delightful transition in the season. The trend reveals a gradual increase in sunlight from the early months of the year, peaking in late spring and slightly tapering off during the height of summer. While July sees the lowest sunshine certainty at just 31%, September reflects a rebound as it approaches the milder autumn months. This combination of golden days and cooler evenings makes it a perfect time for outdoor enthusiasts to enjoy the stunning landscapes of Northern Arizona before winter sets in. With the chance of clear skies still prominent, September offers a wonderful balance between warmth and the gentle onset of fall.
As September arrives in Flagstaff, the days begin to shorten, offering around 12 hours of daylight. This marks a gentle transition from the sun-drenched glory of summer months, where the sun lingered for up to 14 hours in June, July, and August. The gradual decrease in daylight is part of a seasonal rhythm, as the landscape shifts from the vibrant greens of summer to the warm hues of fall. Following September, the daylight will dip further, reflecting nature's preparation for the quieter, introspective months ahead. This ebb and flow not only influences daily life but also sets a scenic backdrop for the stunning autumnal displays that Flagstaff is known for.
As September breezes into Flagstaff, the average wind speed settles at a gentle 2.1 m/s (5 mph). This marks a slight decline from the summer months, where winds were somewhat calmer, particularly in July at 2.0 m/s (4 mph), before making a mild comeback in October. Throughout the year, spring months showcase a gradual increase in wind speeds, peaking in April with 3.6 m/s (8 mph), before softening into the warmer summer days. Observing these trends, it’s evident that Flagstaff experiences a distinct seasonal rhythm in its winds, gently ushering in the fall with a serene whisper as nature transitions into cooler months.
The weather in Flagstaff changes throughout the year, offering a unique experience in each season. Below is a month-by-month comparison of September's weather with other months, highlighting differences in temperature, precipitation, and other key factors. Click on each section to discover seasonal trends in Flagstaff and find detailed weather information for every month.
September and January present strikingly different weather conditions. In September, temperatures range from a chilly minimum of -1°C (31°F) to a warm average of 17°C (63°F), peaking at a hot 33°C (91°F). The month receives about 49 mm (1.9 in) of rainfall over approximately 7 days, coupled with a moderate humidity level of 59%. In contrast, January is considerably colder, with temperatures plummeting to a minimum of -18°C (0°F) and averaging around 0°C (32°F), while the maximum only reaches 14°C (58°F). Rainfall is similar, at 47 mm (1.8 in) over the same 7 days, but the humidity rises to a steeper 80%. For more specifics about January conditions, consider exploring Flagstaff weather in January.
September and February present strikingly different weather conditions. In September, temperatures range from a chilly minimum of -1°C (31°F) to a warm maximum of 33°C (91°F), with an average of 17°C (63°F). Conversely, February experiences much colder temperatures, with a minimum of -19°C (-2°F) and an average of just 1°C (34°F), peaking at a maximum of 17°C (63°F). Precipitation levels are quite similar, with September receiving 49 mm (1.9 in) and February slightly more at 50 mm (2.0 in), both spread over about seven days. Humidity also contrasts between the two months, with September at 59% and February rising to a much higher 83%. For a deeper dive into February weather, check out Flagstaff weather in February.
In comparing the weather of September and March, it is evident that September offers a much warmer climate with average temperatures around 17°C (63°F) and maximums peaking at 33°C (91°F). In contrast, March experiences chillier conditions with an average temperature of only 4°C (39°F) and maximums reaching 20°C (69°F). Additionally, March has higher humidity at 72% and sees slightly more rainfall, totaling 61 mm (2.4 in) over 9 days, compared to September's 49 mm (1.9 in) over 7 days. For a more detailed look at what to expect, check out Flagstaff weather in March.
September and April exhibit distinct weather patterns that reflect the transition between summer and autumn, and winter to spring, respectively. In September, temperatures range significantly, with a minimum of -1°C (31°F) and reaching a maximum of 33°C (91°F), resulting in an average of 17°C (63°F). This month experiences relatively high precipitation of 49 mm (1.9 in) over about 7 days, with humidity averaging 59%. Conversely, April presents cooler temperatures, with a minimum of -7°C (20°F) and a maximum of 26°C (79°F), leading to a lower average of 9°C (49°F). Precipitation in April is lighter at 22 mm (0.9 in) over just 4 days, with a slightly higher humidity level of 63%. For more detailed insights, check out Flagstaff weather in April.
In comparing the weather between September and May, September tends to be warmer overall, with an average temperature of 17°C (63°F) compared to May's average of 13°C (57°F). The maximum temperatures in September can reach up to 33°C (91°F), while May's highs peak at 30°C (86°F). September also experiences more humidity at 59%, compared to 46% in May, which contributes to a noticeably different feel in the air. Precipitation is slightly higher in September, with 49 mm (1.9 in) over 7 days, compared to May's 32 mm (1.3 in) over 6 days. For more detailed weather information for May, you can check Flagstaff weather in May.
In comparing the weather of September and June, it’s evident that September experiences a broader range of temperatures, with a minimum of -1°C (31°F) and a maximum of 33°C (91°F), while June has a milder range, with temperatures ranging from 3°C (37°F) to 35°C (95°F). September also tends to be wetter, receiving 49 mm (1.9 in) of precipitation over 7 days compared to June's relatively dry conditions with only 11 mm (0.4 in) over 2 days. Additionally, humidity levels are higher in September at 59%, versus June's 35%, indicating a more comfortable atmosphere in June. For more detailed information, you can check Flagstaff weather in June.
In comparing the weather between July and September, notable differences emerge. July tends to be warmer, with average temperatures reaching around 21°C (70°F) and maximums soaring to 35°C (95°F). In contrast, September experiences a broader temperature range, with minimums dropping to -1°C (31°F) and maximums peaking at 33°C (91°F), resulting in an average of 17°C (63°F). Additionally, July has significantly higher precipitation, totaling 148 mm (5.8 in) over 16 days, compared to September's 49 mm (1.9 in) over just 7 days. The humidity levels also differ, with July being noticeably drier at 33%, while September reaches a higher humidity of 59%. For more insights into July weather, visit Flagstaff weather in July.
In August, the weather tends to be warmer with minimum temperatures around 9°C (48°F) and an average of 20°C (69°F), while September sees a noticeable drop in minimum temperatures to -1°C (31°F). Despite both months reaching similar maximum temperatures of around 33°C (91°F), September is marked by a cooler average temperature of 17°C (63°F). Additionally, August experiences more precipitation, totaling 69 mm (2.7 in) over 13 days, compared to September's 49 mm (1.9 in) over just 7 days. Humidity levels also differ, with August being more comfortable at 41% compared to September's 59%. For more detailed insights, you can check Flagstaff weather in August.
September weather in Flagstaff features a wider temperature range, with minimums at -1°C (31°F) and maximums reaching up to 33°C (91°F). The average temperature of 17°C (63°F) is accompanied by 49 mm (1.9 in) of precipitation over 7 days, with a humidity level of 59%. In contrast, October brings cooler conditions, marked by a minimum temperature of -8°C (17°F) and a maximum of 26°C (80°F), resulting in an average of 11°C (51°F). Rainfall is less frequent, totaling 34 mm (1.4 in) over just 5 days, and humidity increases to 70%. For more detailed insights, you can check Flagstaff weather in October.
September and November exhibit contrasting weather patterns as temperatures shift dramatically. In September, temperatures range from a chilly minimum of -1°C (31°F) to a warm maximum of 33°C (91°F), with an average of 17°C (63°F). The month experiences moderate precipitation of 49 mm (1.9 in) over 7 days, accompanied by a humidity level of 59%. In contrast, November sees a significant drop in temperature, with a minimum of -16°C (4°F) and an average of 6°C (42°F), peaking at only 20°C (69°F). Although precipitation decreases to 30 mm (1.2 in) over just 3 days, humidity rises to 79%. For more details on weather in November, you can visit Flagstaff weather in November.
In September, the weather is warm and variable, with average temperatures reaching 17°C (63°F) and a maximum of 33°C (91°F), while the nights can cool down to a chilly -1°C (31°F). In contrast, December brings much colder conditions, with average temperatures dropping to just 1°C (33°F) and lows plunging to -20°C (-4°F), making it a stark shift from the previous month. Although September experiences more rain, totaling 49 mm (1.9 in) over 7 days, December sees less precipitation at 36 mm (1.4 in) across 6 days. The humidity also increases in December, reaching 82% compared to 59% in September, contributing to a more frigid feel to the winter air. For more detailed information, check out Flagstaff weather in December.
September in Flagstaff marks a transition into the cooler seasons, offering a delightful blend of temperature variability and refreshing humidity. While daytime highs can reach a warm 33°C (91°F), the evenings welcome a crispness, often dipping near freezing. This month also sees a moderate amount of precipitation over several days, contributing to the lush landscape that characterizes the region. With an average temperature around 17°C (63°F), September provides a perfect backdrop for outdoor adventures, making it distinct from the scorching summer months and the chill of winter. For a deeper dive into the year-round climate patterns in this picturesque city, check out Flagstaff Climate.