Climate averages 1991–2020

Hillsboro weather
in January.

A cold, wet month: the 11th warmest and the 10th driest of the year.

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

Average high 7.9°C Daytime mean, January

Average low 1.8°C Night-time mean, January

Rainfall 172 mm 17 days with ≥1 mm

Daylight 9 h Sunrise to sunset, per day

January is a cold month in Hillsboro: daytime highs average 7.9°C and nights cool to about 1.8°C. By daytime temperature it is the 11th warmest of the 12 months.

Expect about 172 mm of rain on roughly 17 days, which makes January a wet month (the 10th driest of the 12 months). Daylight, from sunrise to sunset, lasts about 9 h 08 min on an average January day.

The nearest other city in this atlas is Beaverton (15 km away). In January its highs average 7.9°C, about as warm as Hillsboro, with 167 mm of rain.

Among the 498 cities listed in the United States, Hillsboro ranks joint 277th of 498 for the warmest January highs and 484th of 498 for the driest January (rainfall, lowest first). The mean January high of those 498 cities is 9.5°C; Hillsboro is 1.5°C cooler than that mean.

From January to February, average highs rise by 1.7°C to 9.7°C, and monthly rainfall falls from 172 mm to 133 mm.

The annual picture

January 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

Hillsboro climate table

1991–2020

Monthly climate averages for Hillsboro, 1991–2020
Month	Average highHigh / low	Average low	Rainfall mm/month	Rain days ≥1 mm/day	Daylight hours/dayDaylight h/day
January, selected	7.9°C1.8°C	1.8°C	172	17.1	9.19 h
February	9.7°C2.1°C	2.1°C	133	14.4	10.310 h
March	12.1°C3.5°C	3.5°C	151	17.3	11.912 h
April	14.6°C5.2°C	5.2°C	115	15.6	13.513 h
May	18.6°C8.4°C	8.4°C	69	10.6	14.915 h
June	21.5°C11.0°C	11.0°C	40	7.2	15.616 h
July	26.6°C13.8°C	13.8°C	11	2.2	15.315 h
August	27.1°C14.4°C	14.4°C	13	2.5	14.114 h
September	23.7°C12.2°C	12.2°C	43	6.0	12.613 h
October	16.7°C8.0°C	8.0°C	107	11.5	11.011 h
November	10.7°C4.2°C	4.2°C	179	17.3	9.610 h
December	7.4°C1.7°C	1.7°C	204	17.5	8.89 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

January in nearby cities

Distance from Hillsboro

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