September Weather in Baltimore, United States

Last updated: February 24, 2025

September in Baltimore showcases a delightful transition from summer to early autumn, with average temperatures resting around 22°C (72°F). The month's peak can reach a sizzling 32°C (89°F), while cooler evenings dip down to a refreshing 9°C (49°F). Rainfall is prominent, with an accumulation of 111 mm (4.4 in) spread over 10 days, contributing to a humidity level of 75% that enhances the lush charm of the city. It's a month where vibrant foliage begins to hint at the colder months ahead, making it a captivating time for locals and visitors alike.

September Temperature in Baltimore

In September, Baltimore experiences a delightful transition as summer begins to wane, bringing about a refreshing change in temperatures. With a minimum of 9°C (49°F) and an average high of 32°C (89°F), the month strikes a perfect balance between warmth and coolness. The average temperature of 22°C (72°F) indicates a comfortable climate ideal for outdoor activities, while the maximum range suggests that late summer heat still holds strong. As the city edges closer to autumn, the cooler evenings provide a welcoming reprieve, making September a wonderful time to explore Baltimore's vibrant neighborhoods and stunning waterfronts.

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

The chart illustrates September temperature patterns in Baltimore, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends.
JanFebMarAprMayJunJulAugSepOctNovDec363945556474807772624841
Data source: Temperature data for Baltimore 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 Baltimore

In September, Baltimore experiences a noteworthy blend of warmth and rainfall, averaging 111 mm (4.4 inches) of precipitation across 10 days. This slight dip in rainfall compared to the preceding months, like August's whopping 143 mm, indicates a gradual transition towards drier fall weather. However, September remains one of the wetter months, contributing to the lush green landscapes that characterize the city. As summer fades, locals can expect more manageable precipitation days, offering a brief respite from the more frequent rain of the preceding months. Overall, it marks a pivotal shift as the city prepares to welcome the crisp autumn air.

September Precipitation Trends in Baltimore

The chart displays monthly precipitation patterns in Baltimore, 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.
JanFebMarAprMayJunJulAugSepOctNovDec701179911414510615114311112390116
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Baltimore

As summer fades away, September in Baltimore brings a slight uptick in humidity, settling at 75%. This month marks a transition, where the heat of July and August gives way to the crispness of autumn. Interestingly, humidity levels have shown a gradual decline from their peak in January (84%) through to August (72%), only to experience a modest rise in September. This trend highlights the city's characteristic shift as it prepares for the cooler months ahead. With October and November bringing higher humidity levels again—reaching 81% and surging to 85% respectively—September acts as a brief interlude of balance, a gentle reminder of the warm days just passed while hinting at the changes to come.

September Average Humidity in Baltimore

This chart illustrates the average monthly humidity levels in Baltimore, 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.
JanFebMarAprMayJunJulAugSepOctNovDec84%83%83%81%78%79%74%72%75%81%85%84%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Baltimore

As September rolls in, Baltimore experiences a UV Index of 8, maintaining its position in the very high exposure category with a burn time of just 15 minutes. This slight decline from August's peak of 9 indicates the onset of autumn, though caution is still essential for outdoor activities. Throughout the summer months, Baltimoreans faced UV levels consistently reaching 10, with burn times as short as 15 minutes. September serves as a reminder that, despite cooler temperatures, harmful UV radiation persists, continuing a trend observed from the spring through early fall. It's crucial to stay vigilant and protect your skin during this time. For more detailed information, visit Baltimore UV Index.

Maximum UV Index Levels in Baltimore for September

The chart shows the monthly maximum UV Index (UVI) for Baltimore 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.
JanFebMarAprMayJunJulAugSepOctNovDec357910101098753
Data source: Baltimore 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 Baltimore

As summer wanes and September settles in Baltimore, the city basks in a splendid 281 hours of sunshine, a delightful encore to the sun-soaked months preceding it. This vibrant month reflects a trend of gradually diminishing daylight as the year progresses, following the peak of 359 hours in July. While September marks a noticeable reduction in sunlight compared to the summer's zenith, it still stands as the sixth sunniest month of the year, offering a golden opportunity for residents to embrace outdoor activities and enjoy the lingering warmth of the season. The subtle transition. encourages a shift from beach days to cozy early autumn evenings, inviting both reflection and celebration of nature's changing palette.

Monthly Sunshine Duration in Baltimore: September Highlighted

The September sunshine duration represents the total number of hours Baltimore 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.
JanFebMarAprMayJunJulAugSepOctNovDec151h182h261h268h297h339h359h329h281h250h226h190h
Data source: Baltimore September Sunshine duration data generated using information from the Copernicus Climate Change Service.

Chance of Sun in Baltimore During September

As September rolls in, Baltimore experiences a notable increase in sunny weather, with a 54% chance of sunshine—the highest for the month in the year. This marks a shift from the summer months, which feature varying sun exposure, with July peaking at 51% but quickly declining into August's 35%. Following the warm summer days, September sets the stage for a refreshing transition into fall, with sunlight becoming more frequent compared to the preceding weeks. Looking ahead, October offers a slight dip to 41%, while November brings a chilly 55%, indicating that even as temperatures drop, sunny days tend to linger. This pattern reveals September as a pivotal moment where summer's warmth meets autumn's crispness, making it a lovely time to enjoy the outdoors in Baltimore.

Percentage of Sunny Days in September in Baltimore

The chart illustrates the percentage of sunny days in Baltimore 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 Baltimore experiences clear skies throughout the year.
JanFebMarAprMayJunJulAugSepOctNovDec46%28%53%46%40%39%51%35%54%41%55%36%
Data source: Baltimore September chance of sun data, generated using information from the Copernicus Climate Change Service.

Daylight Hours in Baltimore in September

As summer fades and autumn approaches, September in Baltimore sees a gradual decline in daylight, offering around 12 hours of bright skies. This month marks a transitional phase, with daylight decreasing from the peak of 14 hours enjoyed in the summer months of June through August. Following the vibrant blooms of spring and the lengthy sunlit days that accompany warmer temperatures, September serves as a gentle reminder of the upcoming changes, as daylight allows for leisurely outdoor activities before the shorter days of fall settle in. The gradual shift in daylight duration highlights the natural rhythm of the seasons, moving from the long, sun-filled days of summer toward the cozy embrace of autumn.

Average Daylight Hours in Baltimore for September

The chart illustrates the variation in daylight duration in Baltimore throughout the year, with September highlighted. It shows the monthly changes in daylight hours, calculated by summing the hours between sunrise and sunset.
JanFebMarAprMayJunJulAugSepOctNovDec9h 45m10h 43m11h 58m13h 15m14h 19m14h 51m14h 34m13h 36m12h 23m11h 7m10h9h 26m
Data source: Baltimore daylight hours, calculated by summing the hours between sunrise and sunset for each day.

September Winds in Baltimore

In September, Baltimore experiences a noticeable shift in wind patterns as the average speed picks up to 3.5 m/s (8 mph), marking a slight increase from the preceding summer months. Following a gentle decline throughout the summer, with July recording its lowest average at 3.0 m/s (7 mph), the winds begin to regain strength as autumn approaches. This seasonal transition not only invigorates the air with a refreshing breeze but also sets the stage for the brisk winds of fall. As Baltimoreers prepare for the changing foliage and cooler temperatures, the September winds remind them of nature's cyclical rhythm, bridging the warmth of summer with the crispness of upcoming autumn.

Average September Wind Speed in Baltimore

The chart displays monthly wind speed patterns in Baltimore, 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.
JanFebMarAprMayJunJulAugSepOctNovDec3.84.14.14.03.73.33.02.63.5 m/s3.73.93.4
Data source: Baltimore September wind data, generated using information from the Copernicus Climate Change Service.

How September Weather in Baltimore Compares to Other Months

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

September and January present striking contrasts in weather. In September, temperatures range from a mild 9°C (49°F) at night to a warm 32°C (89°F) during the day, with an average of 22°C (72°F). The month sees about 111 mm (4.4 in) of rainfall over approximately 10 days, accompanied by a humidity level of 75%. In contrast, January features much colder temperatures, with lows plunging to -13°C (9°F) and daytime highs reaching only 17°C (63°F), resulting in an average of just 2°C (36°F). While January experiences less precipitation at 70 mm (2.8 in) over 8 days, the humidity is slightly higher at 84%. For a more detailed look at the conditions during this time, check out Baltimore weather in January.

September and February present starkly contrasting weather conditions. In September, temperatures range from a mild 9°C (49°F) at night to a warm 32°C (89°F) during the day, with an average of 22°C (72°F). This month experiences about 111 mm (4.4 in) of rainfall over 10 days, accompanied by a humidity level of 75%. In contrast, February brings much colder temperatures, with lows plummeting to -14°C (8°F) and an average of only 4°C (39°F), peaking at 20°C (69°F). Precipitation in February is slightly higher at 117 mm (4.6 in), occurring over 12 days, and humidity is also elevated at 83%. For more insights on the weather patterns during this month, you can visit Baltimore weather in February.

In comparing the weather of September and March, it’s evident that September generally offers warmer temperatures, with an average of 22°C (72°F) compared to March’s cooler average of 7°C (45°F). While September can reach highs of up to 32°C (89°F), March's maximum temperature peaks at 24°C (75°F). Both months experience similar levels of precipitation, with September receiving 111 mm (4.4 in) and March slightly less at 99 mm (3.9 in), both over about 10 days. Additionally, March tends to have a higher humidity level of 83% compared to September's 75%, making it feel a bit more muggy. For more information on March weather specifics, you can check out Baltimore weather in March.

When comparing the weather in September and April, we can see notable differences in temperature and overall climate conditions. September enjoys warmer temperatures, with averages reaching 22°C (72°F) and maximums peaking at 32°C (89°F), whereas April's average is cooler at 13°C (55°F) with maximums reaching 27°C (81°F). Both months experience similar levels of precipitation, with September receiving 111 mm (4.4 in) over about 10 days and April slightly higher at 114 mm (4.5 in) over 11 days. Additionally, April has a higher humidity level at 81% compared to September's 75%. For more detailed information on April weather, you can visit Baltimore weather in April.

When comparing the weather in September and May, a few notable differences emerge. September typically experiences a wider temperature range, with minimums around 9°C (49°F) and average highs reaching 32°C (89°F), while May starts off cooler with lows of 3°C (38°F) and an average maximum of 30°C (87°F). Precipitation is also a factor; September averages 111 mm (4.4 in) over about 10 days, compared to May's 145 mm (5.7 in) across approximately 14 days. Both months have similar humidity levels, with September at 75% and May slightly higher at 78%. For more specific details on May weather, you can visit Baltimore weather in May.

In comparing the weather of September and June, both months experience warm temperatures, with average highs reaching around 32°C (90°F) for June and the same for September. However, September typically has a slightly broader temperature range, with minimums dropping to 9°C (49°F) compared to June's minimum of 11°C (52°F). Both months also see significant humidity levels, with September at 75% and June a bit higher at 79%. In terms of precipitation, September has similar rainfall to June, averaging 111 mm (4.4 in) over 10 days, while June sees 106 mm (4.2 in) over a slightly longer duration of 14 days. For more specific details about June weather, you can visit Baltimore weather in June.

When comparing the weather in September and July, a noticeable difference in temperature is evident. September enjoys a more moderate temperature range, with a minimum of 9°C (49°F) and an average of 22°C (72°F), peaking at 32°C (89°F). In contrast, July is significantly warmer, with minimum temperatures of 17°C (63°F), an average of 27°C (80°F), and maximums reaching 35°C (96°F). Additionally, July experiences higher precipitation levels, totaling 151 mm (6.0 in) over 13 days, compared to September's 111 mm (4.4 in) over 10 days. Humidity remains fairly consistent in both months, hovering around 75% in September and slightly lower at 74% in July. For more details on July weather specifics, check out Baltimore weather in July.

In September, temperatures tend to be cooler compared to August, with a minimum of 9°C (49°F) and an average of 22°C (72°F), while August sees milder lows of 16°C (62°F) and an average of 25°C (78°F). The maximum temperatures in both months are relatively similar, with September reaching up to 32°C (89°F) and August peaking at 33°C (92°F). However, September experiences more rainfall, accumulating 111 mm (4.4 in) over about 10 days, compared to August's 143 mm (5.6 in) over approximately 16 days. Additionally, humidity levels are slightly higher in September at 75%, compared to August's 72%. For more detailed information, check out Baltimore weather in August.

September and October display distinct shifts in weather patterns. In September, temperatures range from a minimum of 9°C (49°F) to an average of 22°C (72°F) and peak at 32°C (89°F), with overall precipitation at 111 mm (4.4 in) over 10 days and humidity sitting at 75%. In contrast, October brings cooler temperatures, with a minimum of 4°C (39°F) and an average of 17°C (63°F), while still reaching highs of 32°C (91°F). Additionally, October experiences slightly higher rainfall at 123 mm (4.8 in) across 11 days, accompanied by increased humidity at 81%. For more detailed insights, check out Baltimore weather in October.

September and November present a striking contrast in weather conditions. In September, temperatures typically range from a pleasant minimum of 9°C (49°F) to a warm maximum of 32°C (89°F), with an average of 22°C (72°F). The month also sees a significant amount of rainfall, with 111 mm (4.4 in) spread over 10 days, accompanied by a humidity level of 75%. In contrast, November experiences much cooler temperatures, with a minimum of -4°C (26°F) and a maximum of 23°C (73°F), leading to an average of only 9°C (48°F). Precipitation decreases to 90 mm (3.6 in) over 8 days, and humidity rises slightly to 85%. For more details on November weather, check out Baltimore weather in November.

September and December present contrasting weather patterns. In September, temperatures range from a minimum of 9°C (49°F) to a maximum of 32°C (89°F), with an average of 22°C (72°F), making it feel warm and fairly humid at 75%. However, it also sees significant rainfall, receiving about 111 mm (4.4 inches) over approximately 10 days. In stark contrast, December experiences much colder temperatures, with a minimum of -9°C (16°F) and a maximum of 17°C (64°F), resulting in an average of just 5°C (41°F). While precipitation in December slightly increases to 116 mm (4.6 inches) over 9 days, the humidity rises to 84%, contributing to a crisp, wintry atmosphere. For additional insights on December's weather, you can visit Baltimore weather in December.

Compare Baltimore's Climate with Cities Worldwide

Conclusion: What to Expect From September Weather in Baltimore

As September unfolds in Baltimore, the weather begins to transition from the sweltering heat of summer to more temperate conditions, making it a unique time for locals and visitors alike. With average temperatures hovering around a pleasant 22°C (72°F) and a striking maximum of 32°C (89°F) on warmer days, the air remains balmy yet comfortable. However, September is also marked by increased humidity levels averaging 75%, contributing to a more tropical feel. While the month experiences rainfall on about 10 days, accumulating to 111 mm (4.4 in), it remains considerably less rainy than the peak summer months. This shift creates a delightful blend of warmth and refreshing breezes, inviting everyone to enjoy outdoor activities before the cooler fall weather sets in. For more insights into what to expect throughout the year, visit Baltimore Climate.