Lake Oswego, OR climate
Lake Oswego has mild winters and pleasant summers. A typical July afternoon reaches 81°, a January night drops to 36°, and about 4 inches of snow falls in a normal winter.
NOAA 1991-2020 climate normals Updated once a decadeWhat a year in Lake Oswego feels like
Winter
Spring
Summer
Fall
Lake Oswego weather by month
Average highs, lows, rain and snow for every month, from NOAA’s 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | Snow on ground | 30-yr range |
|---|---|---|---|---|---|---|---|
| January | 47° | 36° | 6.0" | 1.3" | 20 | 1 | 34° – 46° |
| February | 51° | 37° | 4.5" | 1.4" | 16 | 1 | 37° – 49° |
| March | 56° | 39° | 4.6" | 0 | 18 | 0 | 44° – 52° |
| April | 61° | 42° | 3.5" | 0 | 17 | 0 | 47° – 56° |
| May | 68° | 47° | 2.5" | 0 | 12 | 0 | 52° – 62° |
| June | 73° | 51° | 1.6" | 0 | 9 | 0 | 58° – 69° |
| July | 81° | 56° | 0.4" | 0 | 3 | 0 | 62° – 72° |
| August | 81° | 56° | 0.6" | 0 | 3 | 0 | 65° – 72° |
| September | 76° | 51° | 1.6" | 0 | 7 | 0 | 60° – 66° |
| October | 63° | 45° | 4.0" | 0 | 13 | 0 | 50° – 59° |
| November | 53° | 40° | 6.4" | 0 | 19 | 0 | 40° – 51° |
| December | 46° | 36° | 7.1" | 0.9" | 20 | 0 | 36° – 44° |
| Year | 63° | 45° | 42.8" | 3.6" | 155 | 2 |
“Wet days” have at least 0.01" of rain or melted snow. “Snow on ground” counts days with 1" or more. The 30-year range is the coldest and warmest that month’s average temperature got between 1991 and 2020.
Rain and snow in Lake Oswego
Lake Oswego gets 43 inches of rain and melted snow a year. December is the wettest month and July the driest. Rain or snow falls on about 155 days a year.
About 280 frost-free days a year
In half of years the last 32° night comes by February 25 and the first one by December 1. That leaves about 280 frost-free days for gardens, longer than 94% of U.S. towns.
Heating and cooling a home in Lake Oswego
Engineers use “degree days” to estimate how hard a furnace or air conditioner works. In Lake Oswego, 90% of that work is heating and 10% is cooling, so the furnace matters far more than the air conditioner.
Degree days measure how far each day’s average temperature falls below or rises above 65°, added up over a year. Source: NOAA station normals.
Lake Oswego and its neighbors
Lake Oswego borders 6 towns with climate data. January nights across them vary by 0.4°. Portland has the coldest January nights (36°) and Oak Grove the hottest July afternoons (82°). Lake Oswego’s January low is 36° and its July high 81°.
Temperatures and rain come from NOAA’s 5 km grid, so each town gets its own value.
How Lake Oswego compares
Compared with every U.S. town and city on TownTapestry, each counted once.
Warmer than it used to be
The last 30 years in Lake Oswego averaged 1.2° warmer than the 1900s. The biggest change is in January (+2.8°). The shift is larger than in 52% of U.S. towns.
Change by month1991–2020 average minus 1901–2000 average, at Lake Oswego’s spot on NOAA’s grid
How much a month can swing
A normal is an average, and real years wander around it. February swings the most: between 1991 and 2020 its average temperature ranged from 37° to 49°. September is the most reliable, staying within 6°.
Common questions about Lake Oswego’s climate
What is the coldest month in Lake Oswego?
December, with a typical high of 46° and a low of 36°.
What is the hottest month in Lake Oswego?
August, with a typical high of 81° and a low of 56°. About 11 days a year reach 90°.
How much snow does Lake Oswego get?
About 4 inches in a normal winter, most of it in February.
When is the first frost in Lake Oswego?
In half of years the first 32° night comes by December 1, and the last spring frost by February 25.
What is the rainiest month in Lake Oswego?
December, with 7.1 inches of rain and melted snow. The year totals 43 inches.
Temperatures and rainfall come from NOAA’s gridded climate normals for Lake Oswego itself (about a 3-mile square). Snow, frost dates and day counts come from NOAA’s weather station at Portland Kgw-tv, OR (7 mi) away. Normals are 30-year averages, not a forecast. Source: NOAA NCEI U.S. Climate Normals, 1991–2020 and 1901–2000.