Weather in Lake Oswego, Oregon
Shoots and Sprouts Rise in Ranks. Day 59 of spring. Read this microseason across nine climate regions →
- TodayMay 16Heavy Drizzle51%56°44°
- SundayMay 17Light Drizzle—62°42°
- MondayMay 18Overcast—70°45°
- TuesdayMay 19Overcast—67°48°
- WednesdayMay 20Overcast—70°45°
- ThursdayMay 21Mostly Clear—80°48°
- FridayMay 22Overcast—77°50°
- PM 2.5
- 3.4 μg/m³
- PM 10
- 5.4 μg/m³
- NO₂
- 1.7 μg/m³
- Ozone
- 68.0 μg/m³
- UV Index
- 0.7 Low
When the dew is on the grass, rain will never come to pass.
- Moonrise
- 12:41 PM
- Moonset
- 4:19 AM
- In sign
- ♉︎ Taurus
Shoots and Sprouts Rise in Ranks
Lake Oswego at a glance
- Today vs. normal: 14°F below the seasonal normal for this latitude
- Last frost: May 18 (climatological average for this latitude)
- Microseason: 28 of 72, May 16–20
- Planting window: Direct sow okra, melons, and southern peas. Thin carrot rows.
Right now in the garden
Cool-season window is open
As of May 17, the cool-season window is open or about to open. Direct-sow peas, lettuce, spinach, radishes, and brassicas now. Hold off on warm-season crops until 1–2 weeks after the last spring frost (around May).
Planting calendar
| Month | Plant | Harvest |
|---|---|---|
| January | — | — |
| February | — | — |
| March | — | — |
| April | — | — |
| May | lettuce, peas, spinach, radishes | lettuce, peas, radishes |
| June | lettuce, peas, spinach, radishes, tomatoes, peppers, beans, squash | lettuce, peas, radishes |
| July | tomatoes, peppers, beans, squash | tomatoes, beans, summer squash |
| August | tomatoes, peppers, beans, squash, fall brassicas, garlic (overwinter), carrots | tomatoes, beans, summer squash |
| September | fall brassicas, garlic (overwinter), carrots | tomatoes, beans, summer squash |
| October | — | winter squash, tomatoes (last) |
| November | — | — |
| December | — | — |
A year in weather
Lake Oswego's warmest month is August (~70°F mean) and its coldest is December (~42°F). Rainfall peaks in December (7.3 inches) and bottoms out in July (0.4 inches).
| Month | Mean temp | Precip | Rainy days |
|---|---|---|---|
| January | 42° | 6.4″ | 14 |
| February | 45° | 4.7″ | 10 |
| March | 48° | 4.8″ | 12 |
| April | 53° | 3.6″ | 11 |
| May | 59° | 2.6″ | 8 |
| June | 63° | 1.5″ | 5 |
| July | 69° | 0.4″ | 2 |
| August | 70° | 0.5″ | 2 |
| September | 65° | 1.6″ | 4 |
| October | 55° | 4.0″ | 9 |
| November | 47° | 6.6″ | 13 |
| December | 42° | 7.3″ | 14 |
Regional context
Lake Oswego sits within a warm-summer Mediterranean climate region — a cohort that shares similar temperature ranges, seasonal patterns, and growing conditions across nearby cities.
Similar climates: Portland, OR, Eugene, OR, Salem, OR, Medford, OR, Bend, OR.
Frequently asked
- When does it freeze in Lake Oswego?
- Lake Oswego's last spring frost typically falls around mid-May, and the first fall frost arrives around mid-October.
- What is the rainy season in Lake Oswego?
- December is the wettest month with about 7.3 inches of rain on average; the city receives roughly 44 inches annually.
- What is the warmest month in Lake Oswego?
- August is typically warmest, averaging about 70°F.
- What is the coldest month in Lake Oswego?
- December is typically coldest, averaging about 42°F.
- When can I start a vegetable garden in Lake Oswego?
- Cool-season crops (peas, lettuce) can be sown around the last spring frost (mid-May); warm-season crops (tomatoes, peppers) wait until 1–2 weeks after.
- How many rainy days does Lake Oswego get?
- Lake Oswego averages about 102 rainy days per year.
- What hardiness zone is Lake Oswego?
- Lake Oswego's USDA hardiness zone is determined by its lowest average winter temperature; check the USDA's online lookup with the city ZIP for the current zone designation.
Climate
Lake Oswego, Oregon sits in a warm-summer Mediterranean climate zone. January means hover near 42°F while July averages 69°F — a 27°F seasonal swing.
Across the year, Lake Oswego receives about 44 inches of precipitation spread over roughly 102 rainy days.
The rhythm of the year is set by latitude (45.4°N), proximity to large water bodies, and elevation — all of which shape what grows here, when frost is likely, and what the weather story looks like day to day.