Climate and monthly weather forecastLake Oswego, OR
Climate and monthly weather forecast
The climate of Lake Oswego
Lake Oswego, Oregon, United States, sports a Mediterranean climate with warm summers, distinctively identified as Csb according to the Köppen climate classification. This particular climate system produces moderate temperatures and variable weather conditions year-round.Throughout the year, remarkable variations are observed among different weather parameters. The temperatures, for instance, demonstrate noticeable fluctuations between 35.2°F (1.8°C) in the coldest month of January and a peak of 81.7°F (27.6°C) during the warmest month of August. Humidity diminishes from 83% in January to 63% in August, providing a relief from the otherwise humid days of winter.
Rainfall adds another layer of complexity to the prevailing weather condition in Lake Oswego. A substantially higher amount of rainfall, 4.57" (116mm), is recorded in December compared to mere 0.31" (8mm) in July. The number of days with rain also tracks this pattern, peaking in March with 20.4 days of rainfall and reaching the lowest point in July at 4.8 days.
Uniquely, January, February, and March experience some minor snowfall, adding a touch of white to the otherwise green landscape. In contrast, the sunshine duration increases dramatically from 4.3 hours per day in January to reach a maximum of 11 hours in both July and August.
The best time to visit Lake Oswego
Combine warm temperatures, low rainfall, and extended daylight hours, and it is easy to establish that the best time to visit Lake Oswego is between May and August. During these months, temperatures range from 66.7°F (19.3°C) to the peak of 81.7°F (27.6°C), coupled with the least amount of annual rainfall. With nine to eleven hours of sunshine daily, the city basks in long sunlit days, perfect for outdoor activities and sightseeing.The worst time to visit Lake Oswego
The months between November and January may not present the most desirable weather conditions for a visit to Lake Oswego. During these months, temperatures dip to between 44.4°F (6.9°C) to 46.2°F (7.9°C) and rainfall levels rise significantly, reaching 4.57" (116mm) in December. The limited sunshine hours and the presence of some snow may restrict outdoor activities during this period.Spring weather in Lake Oswego
The spring season, extending from March to May, manifests moderate temperature, with high temperatures increasing from 52.5°F (11.4°C) to 66.7°F (19.3°C), and low temperatures lying between 37.9°F (3.3°C) and 44.1°F (6.7°C). Spring brings relief from the wintery weather as the relative humidity decreases from 81% to 72%. However, rainfall is still prevalent with an inclination from 3.46" (88mm) in March to 1.77" (45mm) in May.Summer weather in Lake Oswego
Summer in Lake Oswego, from June to August, presents warm and welcoming weather. The high temperatures escalate from 72.1°F (22.3°C) in June to a delightful 81.7°F (27.6°C) in August. Minimized rainfall distinguishes the summer season with just 0.31" (8mm) in July, and daylight extends to 15.6 hours in June. Below-average relative humidity levels enhance the comfort during the sunny summer days.Autumn weather in Lake Oswego
Autumn begins in September with a comfortable 74.1°F (23.4°C) temperature, but by November, temperatures drop to 51.1°F (10.6°C). Rainfall gradually increases from 1.69" (43mm) in September to 3.54" (90mm) in November, and daylight hours shrink to 9.5 hours in November. The relative humidity levels of 82% in November signal the onset of the typically humid winter months.Winter weather in Lake Oswego
The winter months in Lake Oswego, from December to February, exhibit the lowest temperatures of the year, dropping from 44.4°F (6.9°C) to 35.2°F (1.8°C). Higher levels of precipitation, achieving 4.57" (116mm) in December, and higher relative humidity levels are noticeable aspects of the season's weather. Occasional snowfall seen in January and February adds to the robust winters, albeit with sunshine still available for approximately 4 hours daily.Weather in January
Kicking off the year, January offers the coldest and the wettest weather conditions in Lake Oswego, Oregon. With temperatures ranging from chilly lows of 35.2°F (1.8°C) to highs of 46.2°F (7.9°C), it provides a stark transition from the festive season into the depths of winter. Weather in January »Weather in February
In February, Lake Oswego witnesses a slight relieving upturn in temperature conditions compared to January, with a gradual climb to an average high of 47.5°F (8.6°C). This respite, though, isn't enough to shake off the grip of winter entirely as the pleasant chill still lingers. Weather in February »Weather in March
The city of Lake Oswego eases into spring in March, providing the month with more mild weather and temperatures reaching an average high of 52.5°F (11.4°C). This month is noticeably different, dominated by a transitionary climate that serves to herald the onset of a warmer season. Weather in March »Weather in April
April introduces the full bloom of spring in Lake Oswego, Oregon with temperatures averaging at a high of 58.6°F (14.8°C). This jump in temperatures compared to March marks the definite end of the cold season. Rain showers are still frequent but increasingly interspersed with days of lovely sunshine. Weather in April »Weather in May
May boasts inviting weather in Lake Oswego with an average temperature high climbing steeply to 66.7°F (19.3°C). This month marks the boundary between spring and summer with every passing day warming up progressively. The rain starts to ease off significantly, leaving a pleasant aroma of fresh soil and bloomed flowers. Weather in May »Weather in June
The charming city of Lake Oswego emerges into the thralls of summer in June, sporting an average temperature high of 72.1°F (22.3°C). A step-up from the milder May, June reveals the early stages of summer in all its sunny glory. Weather in June »Weather in July
July in Lake Oswego means the peak of summer; this is the hottest month, reaching an average high of 80.8°F (27.1°C). Compared to June, July is flooded with sunshine, devouring the rainfall to a minimum. The positively brilliant weather amalgamates with the verdant cityscape, transforming July into a picturesque tableau. Weather in July »Weather in August
August maintains the full form of summer that July established in Lake Oswego with an average high pushing itself to 81.7°F (27.6°C). The weather remains comfortably warm, making it a favorite time for outdoor activities. August carries forward the pattern of azure skies speckled with only a handful of clouds, excessive sunshine, and barely any rain. Weather in August »Weather in September
The city of Lake Oswego eases into the welcoming arms of the fall season in September with marked cooling in the average temperature high to 74.1°F (23.4°C). After two consecutive scorching months, the weather becomes a little more lenient, paving the way to soothing conditions. Weather in September »Weather in October
October carries an autumn freshness in Lake Oswego, Oregon, marked by a drop in the average high temperature to 61.9°F (16.6°C). The substantial temperature cool-off compared to September unveils an atmospheric panorama of fall in full bloom. Weather in October »Weather in November
November ushers in early signs of winter in Lake Oswego with chilling winds dipping the average high temperature further to 51.1°F (10.6°C). Transitioning from a cool October, November presents a noticeable change in the city's weather outlook. Weather in November »Weather in December
December finds Lake Oswego fully entrenched in the grip of winter, sporting temperatures dropping to an average high of 44.4°F (6.9°C). The noticeable drop from November's temperatures reinforces the winter's peak arrival. While rain prevails as the main form of precipitation, it's not unusual to see December dusted with its first few snowflakes. Weather in December »Updated: Jun 4, 2024
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Throughout the year, in Lake Oswego, there are 172.2 rainfall days, and 31.3" (795mm) of precipitation is accumulated.
January through March, November and December are months with snowfall.
In Lake Oswego, during the entire year, snow falls for 6.5 days and aggregates up to 4.13" (105mm) of snow.
January, February, November and December, with an average maximum UV index of 2, are months with the lowest UV index.
With an average relative humidity of 84%, February is the most humid month.
With an average of 4.2h of sunshine, February has the least sunshine of the year.
March is the month with the most snowfall. Snow falls for 1.6 days and accumulates 1.46" (37mm) of snow.
On Sunday, March 10. 2024, at 2:00 am, Daylight Saving Time starts in Lake Oswego, and the time zone changes from PST to PDT. Daylight Saving Time ends Sunday, November 3. 2024, at 2:00 am, and the time zone reverts from PDT to PST.
April through October are months without snowfall.
With an average of 15h and 36min of daylight, June has the longest days of the year.
July is the month with the least rainfall in Lake Oswego. Rain falls for 4.8 days and accumulates 0.31" (8mm) of precipitation.
July is the month with the highest UV index, with an average maximum UV index of 6.
Lake Oswego experiences its highest temperatures in August, with an average peak of 81.7°F (27.6°C) and a low of 54.5°F (12.5°C).
August is the least humid month, with an average relative humidity of 63%.
August has the most sunshine of the year, with an average of 11h of sunshine.
During the coldest month in Lake Oswego, December, temperatures average a high of 44.4°F (6.9°C) and a low of 34.7°F (1.5°C).
December is the month with the most rainfall in Lake Oswego, Oregon. Rain falls for 18.5 days and accumulates 4.57" (116mm) of precipitation.
December has the shortest days of the year, with an average of 8h and 48min of daylight.
Average temperature
Lake Oswego, OR
The warmest month (with the highest average high temperature) is August (81.7°F).
The month with the lowest average high temperature is December (44.4°F).
The month with the highest average low temperature is August (54.5°F).
The coldest month (with the lowest average low temperature) is December (34.7°F).
Average pressure
Lake Oswego, OR
- Average pressure in January:
30.12"Hg - Average pressure in February:
30.08"Hg - Average pressure in March:
30.03"Hg - Average pressure in April:
30.06"Hg - Average pressure in May:
30.03"Hg - Average pressure in June:
30.03"Hg
- Average pressure in July:
30.03"Hg - Average pressure in August:
30"Hg - Average pressure in September:
30.01"Hg - Average pressure in October:
30.05"Hg - Average pressure in November:
30.06"Hg - Average pressure in December:
30.1"Hg
The month with the highest atmospheric pressure is January (30.12"Hg).
The month with the lowest atmospheric pressure is August (30"Hg).
Average wind speed
Lake Oswego, OR
- Average wind speed in January:
6mph - Average wind speed in February:
5.7mph - Average wind speed in March:
5.4mph - Average wind speed in April:
4.8mph - Average wind speed in May:
4.2mph - Average wind speed in June:
4mph
- Average wind speed in July:
4mph - Average wind speed in August:
3.7mph - Average wind speed in September:
3.9mph - Average wind speed in October:
4.7mph - Average wind speed in November:
5.7mph - Average wind speed in December:
5.7mph
The windiest month (with the highest average wind speed) is January (6mph).
The calmest month (with the lowest average wind speed) is August (3.7mph).
Average humidity
Lake Oswego, OR
The month with the highest relative humidity is February (84%).
The month with the lowest relative humidity is August (63%).
Average rainfall
Lake Oswego, OR
- Average rainfall in January:
4.25" - Average rainfall in February:
3.35" - Average rainfall in March:
3.46" - Average rainfall in April:
3.19" - Average rainfall in May:
1.77" - Average rainfall in June:
1.46"
- Average rainfall in July:
0.31" - Average rainfall in August:
0.35" - Average rainfall in September:
1.69" - Average rainfall in October:
3.35" - Average rainfall in November:
3.54" - Average rainfall in December:
4.57"
The wettest month (with the highest rainfall) is December (4.57").
The driest month (with the least rainfall) is July (0.31").
Average rainfall days
Lake Oswego, OR
- Average rainfall days in January:
17.9 days - Average rainfall days in February:
17 days - Average rainfall days in March:
20.4 days - Average rainfall days in April:
18.6 days - Average rainfall days in May:
13.9 days - Average rainfall days in June:
11.4 days
- Average rainfall days in July:
4.8 days - Average rainfall days in August:
5 days - Average rainfall days in September:
10.4 days - Average rainfall days in October:
15.5 days - Average rainfall days in November:
18.8 days - Average rainfall days in December:
18.5 days
The month with the highest number of rainy days is March (20.4 days).
The month with the least rainy days is July (4.8 days).
Average snowfall
Lake Oswego, OR
The month with the highest snowfall is March (1.46").
The months with the least snowfall are April, May, June, July, August, September and October (0").
Average snowfall days
Lake Oswego, OR
- Average snowfall days in January:
1.5 days - Average snowfall days in February:
2.3 days - Average snowfall days in March:
1.6 days - Average snowfall days in April:
0.1 days - Average snowfall days in May:
0 days - Average snowfall days in June:
0 days
- Average snowfall days in July:
0 days - Average snowfall days in August:
0 days - Average snowfall days in September:
0 days - Average snowfall days in October:
0 days - Average snowfall days in November:
0.2 days - Average snowfall days in December:
0.8 days
The month with the highest number of snowfall days is February (2.3 days).
The months with the least snowfall days are May, June, July, August, September and October (0 days).
Average daylight / Average sunshine
Lake Oswego, OR
- Average daylight in January:
9h and 12min - Average daylight in February:
10h and 24min - Average daylight in March:
12h and 0min - Average daylight in April:
13h and 36min - Average daylight in May:
14h and 54min - Average daylight in June:
15h and 36min
- Average daylight in July:
15h and 18min - Average daylight in August:
14h and 0min - Average daylight in September:
12h and 30min - Average daylight in October:
10h and 54min - Average daylight in November:
9h and 30min - Average daylight in December:
8h and 48min
The month with the longest days is June (Average daylight: 15h and 36min).
The month with the shortest days is December (Average daylight: 8h and 48min).
- Average sunshine in January:
4h and 18min - Average sunshine in February:
4h and 12min - Average sunshine in March:
5h and 54min - Average sunshine in April:
7h and 48min - Average sunshine in May:
8h and 48min - Average sunshine in June:
9h and 24min
- Average sunshine in July:
10h and 54min - Average sunshine in August:
11h and 0min - Average sunshine in September:
9h and 18min - Average sunshine in October:
5h and 30min - Average sunshine in November:
4h and 42min - Average sunshine in December:
4h and 24min
The month with the most sunshine is August (Average sunshine: 11h and 0min).
The month with the least sunshine is February (Average sunshine: 4h and 12min).
Average sunshine days
Lake Oswego, OR
- Average sunshine days in January:
11.2 days - Average sunshine days in February:
8.3 days - Average sunshine days in March:
8.7 days - Average sunshine days in April:
8.5 days - Average sunshine days in May:
14.7 days - Average sunshine days in June:
16.3 days
- Average sunshine days in July:
23.9 days - Average sunshine days in August:
23.8 days - Average sunshine days in September:
17.5 days - Average sunshine days in October:
14.1 days - Average sunshine days in November:
9.6 days - Average sunshine days in December:
10.9 days
The month with the most sunshine days is July (23.9 days).
The month with the least sunshine days is February (8.3 days).
Average UV index
Lake Oswego, OR
The month with the highest UV index is July (UV index 6).
The months with the lowest UV index are January, February, November and December (UV index 2).
Average cloud cover
Lake Oswego, OR
The month with the most cloud cover is February (Cloud cover 57).
The month with the least cloud cover is August (Cloud cover 22).
Average visibility
Lake Oswego, OR
The months with the highest visibility are July, August, September and October (6mi).
The months with the lowest visibility are January, February, March, April, May, June, November and December (5mi).
