Climate averages 1991–2020

Harrow weather
in December.

A cold, moderately wet month: the 11th warmest and the joint 9th driest of the year.

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

Average high 7.4°C Daytime mean, December

Average low 2.9°C Night-time mean, December

Rainfall 58 mm 11 days with ≥1 mm

Daylight 8 h Sunrise to sunset, per day

December is a cold month in Harrow: daytime highs average 7.4°C and nights cool to about 2.9°C. By daytime temperature it is the 11th warmest of the 12 months.

Expect about 58 mm of rain on roughly 11 days, which makes December a moderately wet month (the joint 9th driest of the 12 months). Daylight, from sunrise to sunset, lasts about 7 h 55 min on an average December day.

The nearest other city in this atlas is Hayes (9 km away). In December its highs average 7.5°C, about as warm as Harrow, with 58 mm of rain.

Among the 143 cities listed in the United Kingdom, Harrow ranks joint 51st of 143 for the warmest December highs and joint 30th of 143 for the driest December (rainfall, lowest first). The mean December high of those 143 cities is 7.2°C; Harrow is 0.2°C warmer than that mean.

From December to January, average highs fall by 0.3°C to 7.1°C, and monthly rainfall falls from 58 mm to 55 mm.

The annual picture

December 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

Harrow climate table

1991–2020

Monthly climate averages for Harrow, 1991–2020
Month	Average highHigh / low	Average low	Rainfall mm/month	Rain days ≥1 mm/day	Daylight hours/dayDaylight h/day
January	7.1°C2.3°C	2.3°C	55	10.9	8.48 h
February	7.6°C2.2°C	2.2°C	45	9.4	9.910 h
March	10.0°C3.4°C	3.4°C	42	10.2	11.812 h
April	13.0°C5.1°C	5.1°C	49	10.9	13.814 h
May	16.1°C8.2°C	8.2°C	52	9.8	15.616 h
June	19.0°C11.2°C	11.2°C	56	10.0	16.617 h
July	21.2°C13.4°C	13.4°C	54	10.6	16.116 h
August	20.8°C13.3°C	13.3°C	61	10.2	14.615 h
September	18.1°C11.1°C	11.1°C	47	9.0	12.713 h
October	14.2°C8.4°C	8.4°C	58	11.2	10.711 h
November	10.0°C5.1°C	5.1°C	63	11.0	8.99 h
December, selected	7.4°C2.9°C	2.9°C	58	11.2	7.98 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

December in nearby cities

Distance from Harrow

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

London, Archway and Fulham lie in the same rainfall cell, so their rainfall figures are identical to these; temperatures differ because they come from smaller 0.1° cells.