September Weather in Bethlehem, United States

Last updated: February 24, 2025

September in Bethlehem, United States, offers a dynamic blend of weather conditions, making it a captivating time of the year. The month sees maximum temperatures soaring to 33°C (92°F), while the average hovers around a comfortable 20°C (68°F). However, nights can be brisk with minimum temperatures dropping to 3°C (37°F). Rain is a frequent visitor, with 109 mm (4.3 in) of precipitation over 9 days, contributing to a relative humidity of 66%. This mix of warmth and occasional showers creates a unique atmosphere, perfect for enjoying the transition into autumn’s embrace.

September Temperature in Bethlehem

In September, temperatures in Bethlehem begin to transition into the cooler months, bringing a delightful blend of warm days and crisp nights. The average temperature rises to a pleasant 20°C (68°F), creating an ideal environment for outdoor activities. With minimums hovering around 3°C (37°F), the mornings offer a refreshing chill, while maximums can reach up to 33°C (92°F), ensuring that the warmth of summer still lingers. This month beautifully encapsulates the essence of early fall, inviting residents and visitors alike to enjoy the vibrant change in scenery and the comfortable climate.

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

The chart illustrates September temperature patterns in Bethlehem, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends.
JanFebMarAprMayJunJulAugSepOctNovDec323540516170767468574336
Data source: Temperature data for Bethlehem 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 Bethlehem

In September, Bethlehem experiences a significant shift in its precipitation patterns, receiving 109 mm (4.3 in) of rain over just 9 days. This slightly lower amount compared to the summer months reflects a transition towards fall, as temperatures cool and the leaves begin to change. The summer months show a trend of higher precipitation, peaking in August with 140 mm (5.5 in), while September remains robust yet moderate. As the season progresses, the frequency of rainy days decreases, hinting at the stabilization of weather patterns that often accompany autumn in the region. Overall, September serves as a bridge between the hot, humid summer and the cooler, crisper fall, shaping Bethlehem's climate in this transitional month.

September Precipitation Trends in Bethlehem

The chart displays monthly precipitation patterns in Bethlehem, 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.
JanFebMarAprMayJunJulAugSepOctNovDec721089810813910212714010912391108
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Bethlehem

In September, Bethlehem experiences a slight uptick in humidity, with levels at 66%. This marks a subtle rise from the drier summer months of July and August, which recorded 65% and 62% respectively. As the city transitions into fall, humidity levels begin to reclaim some of the moisture lost during the summer, edging closer to October's 79%. Interestingly, as the year progresses, September's humidity sits comfortably between the summer lows and the wetter months that follow, highlighting a seasonal shift that prepares residents for the cooler, more humid autumn days ahead.

September Average Humidity in Bethlehem

This chart illustrates the average monthly humidity levels in Bethlehem, with September's data highlighted for easy comparison. It shows the fluctuation in humidity throughout the year, allowing you to see how September's humidity levels compare to other months.
JanFebMarAprMayJunJulAugSepOctNovDec87%85%85%83%75%74%65%62%66%79%87%85%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Bethlehem

As summer turns to fall, September in Bethlehem maintains a notably high UV Index of 8, indicating that sun protection remains essential. This trend follows the peak summer months when the UV Index reached a maximum of 10 in both June and July. Though September's exposure category is categorized as "very high," the recommended burn time of 15 minutes remains unchanged, mirroring the intense sun exposure earlier in the season. Overall, the gradual decline from summer's extremes showcases the seasonal transition while still highlighting the need for vigilance against harmful UV rays. For more detailed information, check out the full Bethlehem UV Index.

Maximum UV Index Levels in Bethlehem for September

The chart shows the monthly maximum UV Index (UVI) for Bethlehem 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.
JanFebMarAprMayJunJulAugSepOctNovDec356810101098642
Data source: Bethlehem 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 Bethlehem

As summer gracefully yields to autumn, September in Bethlehem emerges as a vibrant month with 265 hours of sunshine, maintaining a commendable position in the annual spectrum of sunlight. This month marks a subtle decline from the peak sunshine of July's 334 hours, yet it still outshines the winter months that follow. The warm days of early fall bring a delightful transition, complemented by the gradual decrease in daylight as the year progresses. With a sunshine duration notably higher than the 202 hours recorded in November and 169 hours in December, September serves as a reminder of the lingering warmth before winter's chill takes hold. As days grow shorter, these sunlit hours become a cherished part of the seasonal shift, inviting residents to relish the beautiful transition from summer to fall.

Monthly Sunshine Duration in Bethlehem: September Highlighted

The September sunshine duration represents the total number of hours Bethlehem 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.
JanFebMarAprMayJunJulAugSepOctNovDec136h172h239h236h266h304h334h301h265h212h203h169h
Data source: Bethlehem September Sunshine duration data generated using information from the Copernicus Climate Change Service.

Chance of Sun in Bethlehem During September

As September rolls into Bethlehem, the likelihood of enjoying sunny weather rises, with a notable probability of 46%. This marks a pleasant increase compared to the summer months, especially August, which holds a comparatively lower chance of sun at just 32%. The trend suggests that as the year progresses into fall, there’s a welcome shift towards clearer skies after the sometimes overcast and humid days of summer. Notably, September's sunny potential positions it favorably against the earlier months of the year, particularly lending itself to more vibrant outdoor experiences before the chill of autumn sets in.

Percentage of Sunny Days in September in Bethlehem

The chart illustrates the percentage of sunny days in Bethlehem 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 Bethlehem experiences clear skies throughout the year.
JanFebMarAprMayJunJulAugSepOctNovDec38%27%55%42%39%38%45%32%46%34%54%30%
Data source: Bethlehem September chance of sun data, generated using information from the Copernicus Climate Change Service.

Daylight Hours in Bethlehem in September

In Bethlehem, United States, the September daylight duration marks a gradual transition toward shorter days, with approximately 12 hours of daylight. This follows a summer peak of 15 hours in June, gradually declining as autumn approaches. The trend shows a steady increase in daylight from the winter months of January and February, where the hours are only 9 and 10, respectively, culminating in the long, sunlit days of May and June. As September rolls in, daylight begins to wane, signaling the onset of autumn and preparing the landscape for the cozy, shorter days of October and November. This rhythmic dance of daylight serves as a reminder of nature’s cycles, inviting residents to relish the lingering golden hours of early fall.

Average Daylight Hours in Bethlehem for September

The chart illustrates the variation in daylight duration in Bethlehem throughout the year, with September highlighted. It shows the monthly changes in daylight hours, calculated by summing the hours between sunrise and sunset.
JanFebMarAprMayJunJulAugSepOctNovDec9h 37m10h 39m11h 58m13h 19m14h 27m15h 1m14h 43m13h 42m12h 24m11h 4m9h 53m9h 17m
Data source: Bethlehem daylight hours, calculated by summing the hours between sunrise and sunset for each day.

September Winds in Bethlehem

As September arrives in Bethlehem, the winds begin to whisper a gentle shift, with an average speed of 2.7 m/s (6 mph). This marks a slight increase from the sluggish breezes of summer, where July and August recorded their lowest speeds of 2.2 m/s and 2.1 m/s, respectively. The transition into fall brings a breath of fresh air, nudging the gusts upwards as the landscape prepares for cooler months. Looking back through the year, one can see a clear trend: wind speeds peak in the spring months of March and April, only to gradually decline over the summer, before experiencing a subtle rejuvenation in September and beyond. This seasonal ebb and flow not only characterizes the region's climate but also enriches the experience of those who savor the changing seasons in Bethlehem.

Average September Wind Speed in Bethlehem

The chart displays monthly wind speed patterns in Bethlehem, 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.
JanFebMarAprMayJunJulAugSepOctNovDec3.23.03.43.12.82.32.22.12.7 m/s2.62.72.7
Data source: Bethlehem September wind data, generated using information from the Copernicus Climate Change Service.

How September Weather in Bethlehem Compares to Other Months

The weather in Bethlehem 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 Bethlehem and find detailed weather information for every month.

September and January present stark contrasts in weather conditions. September features a mild average temperature of 20°C (68°F), with maximums reaching up to 33°C (92°F), while January is much colder, with an average of 0°C (32°F) and minimums plummeting to -20°C (-4°F). Precipitation in September is significantly higher at 109 mm (4.3 in) over 9 days, compared to January's 72 mm (2.8 in) occurring over just 8 days. Additionally, January experiences a higher humidity level at 87%, in contrast to September's 66%. For more details on January's weather, you can check Bethlehem weather in January.

September and February present starkly contrasting weather conditions. In September, temperatures range from a mild 3°C (37°F) to a warm 33°C (92°F), with an average of 20°C (68°F), and the month typically sees about 109 mm (4.3 in) of precipitation over 9 rainy days and 66% humidity. Conversely, February can be quite harsh, with temperatures dipping as low as -19°C (-1°F) and averaging just 1°C (35°F), peaking at 25°C (77°F). This month also experiences similar precipitation levels at 108 mm (4.2 in) but has more rainy days, totaling 12, along with a higher humidity of 85%. For more detailed insights into February weather, you can check Bethlehem weather in February.

September and March showcase starkly contrasting weather patterns. In September, temperatures range from a mild 3°C (37°F) at night to a warm 33°C (92°F) during the day, with an average of 20°C (68°F). The month experiences a fair amount of rainfall, with 109 mm (4.3 in) falling over 9 days and a humidity level of 66%. In contrast, March presents a chilly backdrop, where temperatures can dip as low as -20°C (-4°F) and peak at 26°C (78°F), averaging just 5°C (40°F). Although it has slightly less rainfall at 98 mm (3.9 in) over 11 days, the humidity is notably higher at 85%. For more details, visit Bethlehem weather in March.

When comparing the weather in September and April, a notable difference in temperatures and overall climate can be observed. September typically enjoys milder conditions with average temperatures around 20°C (68°F), peaking at a warm 33°C (92°F), while April experiences cooler temperatures, averaging only 10°C (51°F) and dipping as low as -4°C (25°F). Precipitation levels are similar, with September recording 109 mm (4.3 in) over 9 days and April at 108 mm (4.2 in) spread over 12 days. Furthermore, April tends to be more humid, with an average humidity of 83% compared to September's 66%. For more detailed insights, you can check Bethlehem weather in April.

September and May present contrasting weather patterns. In September, temperatures range from a minimum of 3°C (37°F) to a maximum of 33°C (92°F), with an average of 20°C (68°F), while May sees slightly cooler temperatures, with a minimum of 0°C (32°F) and an average of 16°C (62°F). Though both months can reach similar highs, May tends to be more humid, with a humidity level of 75% compared to September's 66%. Additionally, precipitation is more frequent in May, occurring over 13 days with a total of 139 mm (5.5 in), compared to September's 109 mm (4.3 in) over 9 days. For more details, check out Bethlehem weather in May.

In comparing the weather of September and June, we can see some intriguing differences. September generally has a wider temperature range, with minimums around 3°C (37°F) and maximums reaching up to 33°C (92°F), while June's temperatures are slightly milder with minimums at 6°C (43°F) and maximums peaking at 35°C (94°F). Both months experience notable humidity, with September averaging 66% compared to June's higher average of 73%. Additionally, while September receives slightly more precipitation at 109 mm (4.3 in) over 9 days, June has a comparable precipitation level of 102 mm (4.0 in) over 12 days. For more detailed information on June weather in Bethlehem, you can check Bethlehem weather in June.

Comparing the weather in September and July reveals distinct differences in temperature and precipitation patterns. September experiences a broader temperature range, with minimums as low as 3°C (37°F) and maximums reaching up to 33°C (92°F), while the average temperature hovers around 20°C (68°F). In contrast, July boasts warmer temperatures, with minimums of 13°C (55°F) and maximums peaking at 36°C (96°F), resulting in a higher average of 25°C (76°F). Both months see considerable rainfall, but September has slightly less precipitation at 109 mm (4.3 in) over 9 days compared to July's 127 mm (5.0 in) across 12 days. Humidity levels are relatively similar, with September at 66% and July at 65%. For more detailed information, you can explore Bethlehem weather in July.

When comparing the weather in September to August, we see a noticeable shift in temperature and precipitation patterns. September experiences cooler temperatures, with a minimum of 3°C (37°F) and an average of 20°C (68°F), compared to August's warmer minimum of 11°C (52°F) and average of 23°C (74°F). Both months feature similar maximum temperatures, but September tends to have slightly more rainfall, with 109 mm (4.3 in) over 9 days, while August records 140 mm (5.5 in) over 13 days. Additionally, September has a higher humidity level at 66%, compared to August’s 62%. For more detailed insights, check out Bethlehem weather in August.

September tends to be warmer than October, with average temperatures dipping from a comfortable 20°C (68°F) in September to a cooler 14°C (58°F) in October. Both months experience similar maximum temperatures, peaking at around 33°C (91°F) to 33°C (92°F), but October sees a significant decrease in minimum temperatures, dropping to 1°C (34°F) compared to September's 3°C (37°F). Precipitation increases slightly in October, with 123 mm (4.8 in) over 10 days versus September's 109 mm (4.3 in) over 9 days, contributing to higher humidity levels of 79% in October compared to 66% in September. For more detailed information, you can check Bethlehem weather in October.

September and November present quite a contrast in weather. In September, temperatures can range from a mild 3°C (37°F) at their lowest to a warm high of 33°C (92°F), with an average of 20°C (68°F). The month experiences a moderate precipitation of 109 mm (4.3 in) over nine days, alongside a humidity level of 66%. In contrast, November brings cooler temperatures, with a minimum of -13°C (9°F) and an average of just 6°C (43°F), peaking at 24°C (75°F). The month sees slightly less rain, totaling 91 mm (3.6 in) over the same nine days, but the humidity rises significantly to 87%. For more insights, check out Bethlehem weather in November.

September and December present strikingly different weather patterns. In September, the temperature ranges from a mild minimum of 3°C (37°F) to a warm maximum of 33°C (92°F), with an average of 20°C (68°F). This month experiences some precipitation, totaling 109 mm (4.3 in) over about 9 days, and a humidity level of 66%. In contrast, December sees much cooler temperatures, with a minimum plunging to -14°C (8°F) and an average of just 2°C (36°F), peaking at 17°C (63°F). Precipitation remains similar at 108 mm (4.2 in), but it occurs over more days at 11, along with a higher humidity level of 85%. For a more detailed look, see Bethlehem weather in December.

Compare Bethlehem's Climate with Cities Worldwide

Conclusion: What to Expect From September Weather in Bethlehem

As September rolls in, Bethlehem's weather begins to shift, offering a delightful transition from the sweltering heat of summer to the more temperate conditions of fall. With average temperatures settling comfortably around 20°C (68°F), the city sees a noticeable reduction in the extreme heat, while still enjoying occasional warm days that can reach up to 33°C (92°F). This month is marked by increased humidity and scattered rainfall, resulting in a total of 109 mm over about nine days, which helps nurture the vibrant changes in the landscape. For those keen on exploring Bethlehem during this transitional season, understanding the weather nuances is essential. To learn more about how September fits into the broader climate patterns, check out Bethlehem Climate.