Climate averages 1991–2020

Plymouth weather
in September.

A mild, moderately wet month: the 4th warmest and one of the driest of the year.

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

Average high 17.4°C Daytime mean, September

Average low 12.5°C Night-time mean, September

Rainfall 61 mm 10 days with ≥1 mm

Daylight 13 h Sunrise to sunset, per day

September is a mild month in Plymouth: daytime highs average 17.4°C and nights cool to about 12.5°C. By daytime temperature it is the 4th warmest of the 12 months.

Expect about 61 mm of rain on roughly 10 days, which makes September a moderately wet month (one of the driest months of the year). Daylight, from sunrise to sunset, lasts about 12 h 41 min on an average September day.

The nearest other city in this atlas is Exeter (59 km away). In September its highs average 17.5°C, about as warm as Plymouth, with 53 mm of rain.

Among the 143 cities listed in the United Kingdom, Plymouth ranks joint 74th of 143 for the warmest September highs and joint 99th of 143 for the driest September (rainfall, lowest first). The mean September high of those 143 cities is 17.3°C; Plymouth is 0.2°C warmer than that mean.

From September to October, average highs fall by 3.0°C to 14.4°C, and monthly rainfall rises from 61 mm to 104 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

Plymouth climate table

1991–2020

Monthly climate averages for Plymouth, 1991–2020
Month	Average highHigh / low	Average low	Rainfall mm/month	Rain days ≥1 mm/day	Daylight hours/dayDaylight h/day
January	8.7°C4.9°C	4.9°C	102	15.5	8.69 h
February	8.7°C4.4°C	4.4°C	77	12.0	10.010 h
March	10.2°C5.2°C	5.2°C	67	11.9	11.812 h
April	12.3°C6.5°C	6.5°C	63	11.5	13.814 h
May	15.0°C9.2°C	9.2°C	61	10.7	15.415 h
June	17.6°C11.9°C	11.9°C	61	10.6	16.316 h
July	19.4°C13.9°C	13.9°C	61	10.5	16.016 h
August	19.4°C14.1°C	14.1°C	69	11.2	14.515 h
September, selected	17.4°C12.5°C	12.5°C	61	10.3	12.713 h
October	14.4°C10.3°C	10.3°C	104	14.5	10.811 h
November	11.3°C7.6°C	7.6°C	112	15.4	9.19 h
December	9.3°C5.6°C	5.6°C	109	15.1	8.18 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 Plymouth

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 Plymouth) is explained once on the Plymouth year overview and on the Sources, method and limits page.