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Forest Grove, Oregon climate

Csb Warm-summer Mediterranean

Forest Grove has a seasonal cool-temperate climate (Warm-summer Mediterranean, Köppen Csb). The hottest month is August with an average daily high near 82°F, while the coldest is December averaging around 33°F at night. Precipitation totals about 47 inches a year and is strongly seasonal — December alone averages 8.7 inches while July barely receives 0.32 inches. Snow is occasional (3 inches of snow per year on average).

☀️ Summers

Warm

Highs near 82°F in August.

About 22 days a year above 90 °F

❄️ Winters

Chilly

Lows near 33°F in December.

About 58 freezing nights a year

🌧️ Rain

Wet

About 47 in of rain a year.

Wettest in December

⛅ Sky & trend

Often cloudy

Cloudy skies much of the year.

−0.8 °F vs 50 years ago

Temperature & precipitation

Daily high–low temperature range with the monthly average, plus monthly precipitation · 1991–2020 normals · hover a month for the exact figures

Clear vs cloudy days

Share of days each month that are clear, partly cloudy or cloudy · 1991–2020 · hover a month for the day counts

Forest Grove climate normals (1991–2020)

	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Avg high (°F)	45	49	55	60	68	73	81	82	76	63	51	44
Avg temp (°F)	39	41	45	50	57	61	68	68	62	52	44	38
Avg low (°F)	33	33	36	39	45	50	54	54	49	42	36	33
Precipitation (in)	7.2	5.8	5.0	3.3	2.2	1.4	0.3	0.5	1.3	3.7	7.2	8.7
Snowfall (in)	0.6	0.6	—	—	—	—	—	—	—	0.2	—	1.3

Jan – Jun	Jan	Feb	Mar	Apr	May	Jun
Avg high (°F)	45	49	55	60	68	73
Avg temp (°F)	39	41	45	50	57	61
Avg low (°F)	33	33	36	39	45	50
Precipitation (in)	7.2	5.8	5.0	3.3	2.2	1.4
Snowfall (in)	0.6	0.6	—	—	—	—

Jul – Dec	Jul	Aug	Sep	Oct	Nov	Dec
Avg high (°F)	81	82	76	63	51	44
Avg temp (°F)	68	68	62	52	44	38
Avg low (°F)	54	54	49	42	36	33
Precipitation (in)	0.3	0.5	1.3	3.7	7.2	8.7
Snowfall (in)	—	—	—	0.2	—	1.3

How often — frequency of weather events

	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Days with measurable rain (days)	16	13	16	14	10	7	2	3	5	11	15	16
Days with high ≥ 90°F (days)	—	—	—	—	1	2	7	8	3	0.1	—	—
Days with low ≤ 32°F (days)	13	12	8	3	0.2	0.0	—	0.0	—	2	9	12
Days with snowfall ≥ 1 in (days)	0.2	0.1	—	—	—	—	—	—	—	0.0	—	0.3

Jan – Jun	Jan	Feb	Mar	Apr	May	Jun
Days with measurable rain (days)	16	13	16	14	10	7
Days with high ≥ 90°F (days)	—	—	—	—	1	2
Days with low ≤ 32°F (days)	13	12	8	3	0.2	0.0
Days with snowfall ≥ 1 in (days)	0.2	0.1	—	—	—	—

Jul – Dec	Jul	Aug	Sep	Oct	Nov	Dec
Days with measurable rain (days)	2	3	5	11	15	16
Days with high ≥ 90°F (days)	7	8	3	0.1	—	—
Days with low ≤ 32°F (days)	—	0.0	—	2	9	12
Days with snowfall ≥ 1 in (days)	—	—	—	0.0	—	0.3

Sky & atmosphere

	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Cloud cover (%)	76	74	76	75	70	64	43	43	49	63	75	78
Clear days (≤ 30% cloud)	3	4	3	3	5	6	13	13	12	7	3	2
Partly cloudy days (30–70%)	7	5	6	6	7	9	10	10	7	7	6	6
Cloudy days (≥ 70%)	21	19	22	21	19	15	8	8	11	17	21	22
Relative humidity (%)	94	91	89	86	84	82	77	74	76	84	92	94
Wind speed (mph)	1.4	1.4	1.4	1.3	1.2	1.2	1.2	1.2	1.2	1.3	1.4	1.4

Jan – Jun	Jan	Feb	Mar	Apr	May	Jun
Cloud cover (%)	76	74	76	75	70	64
Clear days (≤ 30% cloud)	3	4	3	3	5	6
Partly cloudy days (30–70%)	7	5	6	6	7	9
Cloudy days (≥ 70%)	21	19	22	21	19	15
Relative humidity (%)	94	91	89	86	84	82
Wind speed (mph)	1.4	1.4	1.4	1.3	1.2	1.2

Jul – Dec	Jul	Aug	Sep	Oct	Nov	Dec
Cloud cover (%)	43	43	49	63	75	78
Clear days (≤ 30% cloud)	13	13	12	7	3	2
Partly cloudy days (30–70%)	10	10	7	7	6	6
Cloudy days (≥ 70%)	8	8	11	17	21	22
Relative humidity (%)	77	74	76	84	92	94
Wind speed (mph)	1.2	1.2	1.2	1.3	1.4	1.4

Methodology & sources

Temperature & precipitation — the official 1991–2020 climate normals from NOAA's U.S. Climate Normals, measured at Forest Grove (NOAA GHCN station USC00352997), inside the city.

Cloud, humidity, wind & sunshine — modelled estimates from NASA POWER, NASA's satellite-and-reanalysis climatology. This is the standard global source for atmospheric variables, which are not measured at most weather stations.

How we build these numbers →