Climate averages 1991–2020

Baltimore weather
in September.

A warm, wet month: the 4th warmest and the wettest of the year.

Long-term climate patterns, not a forecast for a particular trip.

Average high 24.8°C Daytime mean, September

Average low 16.6°C Night-time mean, September

Rainfall 120 mm 9 days with ≥1 mm

Daylight 12 h Sunrise to sunset, per day

September is a warm month in Baltimore: daytime highs average 24.8°C and nights cool to about 16.6°C. By daytime temperature it is the 4th warmest of the 12 months.

Expect about 120 mm of rain on roughly 9 days, which makes September a wet month (the wettest month of the year). Daylight, from sunrise to sunset, lasts about 12 h 29 min on an average September day.

The nearest other city in this atlas is Columbia (Maryland), United States (20 km away). In September its highs average 24.6°C, about as warm as Baltimore, with 116 mm of rain.

Among the 498 cities listed in the United States, Baltimore ranks joint 320th of 498 for the warmest September highs and joint 445th of 498 for the driest September (rainfall, lowest first). The mean September high of those 498 cities is 26.9°C; Baltimore is 2.1°C cooler than that mean.

From September to October, average highs fall by 6.2°C to 18.6°C, and monthly rainfall falls from 120 mm to 102 mm.

The annual picture

September in context

30-year average

Average highAverage low°C

Monthly rainfall

Average total · mm

Averages from hourly ERA5 reanalysis data. Actual weather varies from year to year. How these numbers are calculated

Every month, side by side

Baltimore climate table

1991–2020

Monthly climate averages for Baltimore, 1991–2020
Month	Average highHigh / low	Average low	Rainfall mm/month	Rain days ≥1 mm/day	Daylight hours/dayDaylight h/day
January	4.8°C-2.9°C	-2.9°C	90	9.0	9.710 h
February	6.4°C-2.5°C	-2.5°C	84	9.2	10.711 h
March	10.9°C1.3°C	1.3°C	114	10.5	11.912 h
April	17.2°C7.0°C	7.0°C	97	10.4	13.213 h
May	22.2°C12.7°C	12.7°C	96	11.0	14.314 h
June	27.0°C18.0°C	18.0°C	90	10.9	14.915 h
July	29.6°C21.0°C	21.0°C	97	11.4	14.615 h
August	28.6°C20.2°C	20.2°C	93	10.4	13.714 h
September, selected	24.8°C16.6°C	16.6°C	120	9.4	12.512 h
October	18.6°C10.2°C	10.2°C	102	8.4	11.211 h
November	12.3°C4.2°C	4.2°C	86	8.3	10.110 h
December	7.1°C-0.4°C	-0.4°C	109	9.6	9.59 h

Rainfall is the average of the 30 separate monthly totals. A rain day is a local calendar day with at least 1 mm of precipitation. Daylight is the calculated sunrise-to-sunset length, not measured sunshine.

Compare places

September in nearby cities

Distance from Baltimore

Read the numbers correctly

Climate, not a promise.

These patterns help compare months. They cannot tell you the weather on a specific day of your trip.

Sources, method and limits

How these numbers are made (what the highs, lows and rain days mean, the sources and the model cell used for Baltimore) is explained once on the Baltimore year overview and on the Sources, method and limits page.