Portland climate: monthly averages: annual mean temperature 10.4 C; warmest month Aug (19.7 C); coldest month Dec (3.1 C).
Annual mean temperature: 10.4 C
Warmest month: Aug (19.7 C)
Coldest month: Dec (3.1 C)
Wettest month: Dec (8.10 mm/day)
All-time record high: 40.6 C
All-time record low: -13.4 C
Everything below is collected in one spot so you do not have to cross-check Portland climate: monthly averages by hand. The gap between Dec and Aug is 16.6 C here: 3.1 C against 19.7 C. No month dominates: the wettest is Dec at 8.10 mm/day, the driest Jul at 0.35 mm/day. Taken together that is roughly 1,484 mm of rain a year for the grid cell. Every run re-reads the source and only rewrites this page when a figure actually changed. The table underneath carries the per-month breakdown; the related pages cover the same dataset nearby.
Annual mean temperature 10.4 C
Warmest month Aug (19.7 C)
Coldest month Dec (3.1 C)
Wettest month Dec (8.10 mm/day)
All-time record high 40.6 C
All-time record low -13.4 C
Annual precipitation 1,486 mm / year
Coordinates 45.52345, -122.67621
Population 652,503
Average monthly temperature and rainfall in Portland
Month
Mean temp (C)
Rain (mm/day)
Record high (C)
Record low (C)
Jan
3.5
6.97
16.7
-13.4
Feb
4.1
5.09
18.8
-9.6
Mar
6.3
5.74
23.4
-5.4
Apr
8.5
3.98
28.7
-2.7
May
12.2
2.56
33.9
0.5
Jun
14.9
1.83
37.8
4.0
Jul
18.9
0.35
40.6
7.0
Aug
19.7
0.63
40.1
6.6
Sep
16.5
1.90
38.5
2.1
Oct
10.9
4.43
30.7
-4.2
Nov
6.1
7.24
19.3
-9.4
Dec
3.1
8.10
15.9
-12.5
What the Portland climate table shows
Values are multi-decadal climatological averages for the 45.52345, -122.67621 grid cell, not a single year. Rain is the daily mean, so a value of 2.00 mm/day is about 60 mm across a 30-day month. Averages smooth over extremes, so use them for planning rather than for what to pack for next Tuesday.
Frequently asked questions
Is Portland climate data a forecast?
No. These are multi-decadal averages for the grid cell, not a prediction for any particular year.
Why do the numbers differ from a weather app?
An app shows one location on one day. These are long-run averages, so they smooth out single hot or cold spells.