Sumner, United States experiences average highs of 16°C (61°F) and lows of 7°C (45°F) throughout the year. Rainfall is frequent, averaging about 13 rainy days per month. Average highs have stayed broadly stable across the available records.
Sumner, United States Weather & Climate 2026
Monthly climate averages for Sumner, United States. Based on 10-year ERA5 reanalysis data.
Climate Overview
Drier season: Apr–Oct 
Wetter season: Jan–Dec At-a-Glance Climate Summary
Live Weather & Air Quality
Key figures
Climate Score
5.3/10
Best: June, July, August, September
UV Index
4
Low
Temperature 16°C / 7°C
Feels Like 14°C / 5°C
Rainy Days 13
Rainfall 116 mm
Sunshine 8 h
Humidity 79%
Wind Speed 14 km/h
Dew Point 8°C
Snow Days 8 days
Frost Days 6 days
Hottest Month
26°C
August
Avg Low15°C
Rain4days
Coldest Month
1°C
February
Avg High8°C
Rain17days
Driest Month
3days
July
Avg High26°C
Avg Low14°C
Windiest Month
16 km/h
February (Gusts 38)
Worst Time to Visit
Consider avoiding January, February, December due to heavy rainfall.
Sun Position
Sunrise 05:14
Daylight 15.9h
Sunset 21:08
Live conditions—
Sumner on the map · live conditions
Sumner, United States
- Continent
- Americas
- Country
- United States
- City
- Sumner
- Population
- 9.7K
- Elevation
- 23 m
- Coordinates
- 47.20°, -122.24°
Seasonal Breakdown
Spring
Mar–May
Avg High 15°C
Avg Low 5°C
Rain 15 days/mo
Summer
Jun–Aug
Avg High 24°C
Avg Low 13°C
Rain 6 days/mo
3/3 best months
Autumn
Sep–Nov
Avg High 16°C
Avg Low 8°C
Rain 15 days/mo
1/3 best months
Winter
Dec–Feb
Avg High 8°C
Avg Low 2°C
Rain 18 days/mo
Climate Charts
Based on historical averages (2016–2025)
Monthly Temperatures
HighLowShaded bands show the typical range across the available yearly records.
Line chart showing monthly temperatures. Jan: 8°C / 2°C . Feb: 8°C / 1°C . Mar: 11°C / 3°C . Apr: 15°C / 5°C . May: 19°C / 9°C . Jun: 22°C / 11°C . Jul: 26°C / 14°C . Aug: 26°C / 15°C . Sep: 22°C / 12°C . Oct: 16°C / 8°C . Nov: 11°C / 5°C . Dec: 8°C / 2°C .
Monthly Rainfall
Rainfall
Bar chart showing monthly rainfall. Jan: 197 mm. Feb: 163 mm. Mar: 140 mm. Apr: 109 mm. May: 67 mm. Jun: 59 mm. Jul: 13 mm. Aug: 18 mm. Sep: 67 mm. Oct: 144 mm. Nov: 195 mm. Dec: 218 mm.
Monthly Humidity
Humidity
Line chart showing monthly humidity. Jan: 86%. Feb: 84%. Mar: 82%. Apr: 78%. May: 76%. Jun: 73%. Jul: 67%. Aug: 69%. Sep: 76%. Oct: 83%. Nov: 87%. Dec: 88%.
Monthly Wind Speed
Wind SpeedGusts
Bar chart showing monthly wind speed. Jan: 14 km/h . Feb: 16 km/h . Mar: 15 km/h . Apr: 15 km/h . May: 13 km/h . Jun: 13 km/h . Jul: 11 km/h . Aug: 12 km/h . Sep: 12 km/h . Oct: 14 km/h . Nov: 15 km/h . Dec: 15 km/h .
Sunshine
Sunshine
Sunshine: Jan: 4h. Feb: 5h. Mar: 8h. Apr: 9h. May: 11h. Jun: 12h. Jul: 13h. Aug: 12h. Sep: 10h. Oct: 7h. Nov: 5h. Dec: 4h.
UV Index
UV Index
Bar chart showing monthly UV index. Jan: UV 1. Feb: UV 2. Mar: UV 3. Apr: UV 5. May: UV 6. Jun: UV 7. Jul: UV 7. Aug: UV 6. Sep: UV 5. Oct: UV 3. Nov: UV 2. Dec: UV 1.
Monthly Daylight Hours
Daylight12h reference
Monthly Dew Point & Comfort
Dew Point Dry Comfortable Humid Muggy Oppressive
Snow Days
Snow DaysSnowfall
Snow Days: Jan: 7 days. Feb: 12 days. Mar: 9 days. Apr: 4 days. May: 0 days. Jun: 0 days. Jul: 0 days. Aug: 0 days. Sep: 0 days. Oct: 0 days. Nov: 4 days. Dec: 10 days.
Climate Trends
Average highs have stayed broadly stable across the available records. Average rainfall is trending drier by about 11 mm.
2016 to 2025
Avg high Avg rainfall
Climate summary
| Last 12 months | All years | |
|---|---|---|
| Hottest month | Jul 2025 · 27°C | Aug · 26°C |
| Coldest month | Feb 2025 · 0°C | Feb · 1°C |
| Wettest month | Dec 2025 · 352 mm | Dec · 218 mm |
| Windiest month | Dec 2025 · 19 km/h | Feb · 16 km/h |
Month-by-Month Weather Table
January
Wet 
February
Poor March
Wet April
Fair May
Good June best
Excellent July best
Excellent August best
Excellent September best
Excellent October
Fair November
Wet December
Wet | Month | Temp | Feels Like | Rain | Sun | Humidity | UV | Status | Details |
|---|---|---|---|---|---|---|---|---|
| January | 8°C / 2°C | 6°C / -2°C | 18days (197 mm) Wet | 4.2h Fair | 86% Very Muggy | 1.4 Low | Wet | View Details |
| February | 8°C / 1°C | 5°C / -2°C | 17days (163 mm) Wet | 5.3h Fair | 84% Humid | 2 Low | Poor | View Details |
| March | 11°C / 3°C | 9°C / -1°C | 18days (140 mm) Wet | 7.6h Good | 82% Humid | 3.4 Moderate | Wet | View Details |
| April | 15°C / 5°C | 13°C / 2°C | 16days (109 mm) Wet | 9.2h Good | 78% Humid | 5 Moderate | Fair | View Details |
| May | 19°C / 9°C | 18°C / 7°C | 11days (67 mm) Wet | 10.6h Excellent | 76% Humid | 5.7 High | Good | View Details |
| June best | 22°C / 11°C | 22°C / 10°C | 10days (59 mm) Wet | 11.5h Excellent | 73% Muggy | 6.5 High | Excellent | View Details |
| July best | 26°C / 14°C | 26°C / 14°C | 3days (13 mm) Excellent | 12.6h Excellent | 67% Muggy | 7 High | Excellent | View Details |
| August best | 26°C / 15°C | 27°C / 15°C | 4days (18 mm) Good | 11.5h Excellent | 69% Muggy | 6 High | Excellent | View Details |
| September best | 22°C / 12°C | 22°C / 11°C | 9days (67 mm) Wet | 9.7h Good | 76% Humid | 4.8 Moderate | Excellent | View Details |
| October | 16°C / 8°C | 14°C / 6°C | 16days (144 mm) Wet | 7.1h Good | 83% Humid | 3 Moderate | Fair | View Details |
| November | 11°C / 5°C | 9°C / 2°C | 19days (195 mm) Wet | 4.7h Fair | 87% Very Muggy | 1.7 Low | Wet | View Details |
| December | 8°C / 2°C | 5°C / -1°C | 19days (218 mm) Wet | 3.6h Poor | 88% Very Muggy | 1.1 Low | Wet | View Details |
Compare Nearby City Climates
Frequently Asked Questions
The best months to visit Sumner are June, July, August, September, when temperatures are comfortable and rainfall is at its lowest. This is based on 10-year climate averages for Sumner, scoring temperature, rainfall, humidity, and sunshine hours.
The hottest month in Sumner is August, with average daytime highs of 26°C (79°F). Plan outdoor activities for early morning or late afternoon if visiting during this period.
The coldest month in Sumner is February, with average overnight lows of 1°C (34°F). Pack warm layers and expect shorter daylight hours during this period.
The wettest month in Sumner is December, averaging 218mm of precipitation across 19 rainy days. An umbrella or waterproof jacket is essential.
The rainy season in Sumner runs through November, December, January, March, with the heaviest rainfall in November. Based on 10-year averages for Sumner.
Sumner receives approximately 98 sunshine hours per year. The sunniest month is July with around 13 hours. Based on climate data for Sumner.
The least favorable months to visit Sumner are January, February, December, primarily due to heavy rainfall. For the best conditions, consider June, July, August, September instead.
The annual average UV index in Sumner is 4, classified as moderate. Standard sun protection (sunscreen, hat) is recommended during prolonged outdoor exposure.
Average humidity in Sumner is 79%, classified as humid. Humidity levels are generally comfortable and should not affect outdoor activities for most people.
Yes, Sumner receives snow. Months with snowfall average 8 snow days and 11 cm (4 in) of accumulation, with about 6 frost days during winter.
Average wind speeds in Sumner are 14 km/h (9 mph). The windiest month is February with peak winds reaching 16 km/h (10 mph) (gusts up to 38 km/h / 24 mph).
Sumner averages 4 clear-sky days per month with overall cloud cover around 65%. The clearest skies occur in July.
The annual average dew point in Sumner is 8°C (46°F), which feels dry and comfortable. Outdoor activities are comfortable year-round from a humidity standpoint.
Sumner has a Warm-Summer Mediterranean climate, classified as Csb under the Köppen system. Temperate climates have mild winters and warm summers, with rainfall spread across the year and four distinct seasons.
The 'feels like' temperature in Sumner ranges from 5°C (41°F) to 14°C (57°F) on average. The 'feels like' temperature closely matches the actual temperature throughout most of the year.
Yes, June is a great time to visit Sumner. It earns a climate score of 8.2/10 with Excellent.
For June in Sumner, pack Warm evening layer, Umbrella, Waterproof jacket, Sunscreen (SPF 30+), Sunglasses. With average highs of 22°C (71°F) and 10 rainy days, these essentials will keep you comfortable.
Data Source
Climate data derived from ERA5 reanalysis (ECMWF), averaged over 2016–2025. Sea surface temperature from marine reanalysis data. Climate scores and seasonal estimates are computed by WorldStats.
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