Affton, United States experiences average highs of 19°C (66°F) and lows of 10°C (50°F) throughout the year. Rainfall is moderate, averaging about 10 rainy days per month. Sunshine is abundant, averaging about 9 hours per day. Average highs have stayed broadly stable across the available records.
Affton, United States Weather & Climate 2026
Monthly climate averages for Affton, United States. Based on 10-year ERA5 reanalysis data.
Climate Overview
Drier season: Jan–Dec 
Wetter season: Mar–Aug At-a-Glance Climate Summary
Live Weather & Air Quality
Key figures
Climate Score
5.6/10
Best: May, June, August, September, October
UV Index
5
Low
Temperature 19°C / 10°C
Feels Like 19°C / 8°C
Rainy Days 10
Rainfall 95 mm
Sunshine 9 h
Humidity 68%
Wind Speed 17 km/h
Dew Point 9°C
Snow Days 3 days
Frost Days 12 days
Hottest Month
31°C
July
Avg Low22°C
Rain13days
Coldest Month
-3°C
January
Avg High5°C
Rain8days
Driest Month
7days
September
Avg High28°C
Avg Low18°C
Windiest Month
20 km/h
April (Gusts 44)
Worst Time to Visit
Consider avoiding January, February, December due to very cold temperatures.
Sun Position
Sunrise 05:38
Daylight 14.8h
Sunset 20:28
Live conditions—
Affton on the map · live conditions
Affton, United States
- Continent
- Americas
- Country
- United States
- City
- Affton
- Population
- 20.3K
- Elevation
- 188 m
- Coordinates
- 38.55°, -90.33°
Seasonal Breakdown
Spring
Mar–May
Avg High 19°C
Avg Low 9°C
Rain 12 days/mo
1/3 best months
Summer
Jun–Aug
Avg High 30°C
Avg Low 21°C
Rain 11 days/mo
2/3 best months
Autumn
Sep–Nov
Avg High 20°C
Avg Low 11°C
Rain 8 days/mo
2/3 best months
Winter
Dec–Feb
Avg High 7°C
Avg Low -2°C
Rain 8 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: 5°C / -3°C . Feb: 9°C / -2°C . Mar: 15°C / 4°C . Apr: 19°C / 8°C . May: 24°C / 15°C . Jun: 30°C / 20°C . Jul: 31°C / 22°C . Aug: 30°C / 21°C . Sep: 28°C / 18°C . Oct: 21°C / 11°C . Nov: 13°C / 4°C . Dec: 8°C / 0°C .
Monthly Rainfall
Rainfall
Bar chart showing monthly rainfall. Jan: 78 mm. Feb: 71 mm. Mar: 120 mm. Apr: 134 mm. May: 129 mm. Jun: 87 mm. Jul: 107 mm. Aug: 114 mm. Sep: 80 mm. Oct: 84 mm. Nov: 70 mm. Dec: 64 mm.
Monthly Humidity
Humidity
Line chart showing monthly humidity. Jan: 69%. Feb: 66%. Mar: 65%. Apr: 65%. May: 71%. Jun: 67%. Jul: 71%. Aug: 72%. Sep: 68%. Oct: 66%. Nov: 68%. Dec: 70%.
Monthly Wind Speed
Wind SpeedGusts
Bar chart showing monthly wind speed. Jan: 18 km/h . Feb: 19 km/h . Mar: 20 km/h . Apr: 20 km/h . May: 17 km/h . Jun: 15 km/h . Jul: 13 km/h . Aug: 13 km/h . Sep: 13 km/h . Oct: 17 km/h . Nov: 17 km/h . Dec: 18 km/h .
Sunshine
Sunshine
Sunshine: Jan: 6h. Feb: 7h. Mar: 8h. Apr: 9h. May: 10h. Jun: 12h. Jul: 12h. Aug: 11h. Sep: 10h. Oct: 8h. Nov: 7h. Dec: 6h.
UV Index
UV Index
Bar chart showing monthly UV index. Jan: UV 3. Feb: UV 4. Mar: UV 5. Apr: UV 6. May: UV 7. Jun: UV 7. Jul: UV 8. Aug: UV 7. Sep: UV 6. Oct: UV 4. Nov: UV 3. Dec: UV 2.
Monthly Daylight Hours
Daylight12h reference
Monthly Dew Point & Comfort
Dew Point Dry Comfortable Humid Muggy Oppressive
Snow Days
Snow DaysSnowfall
Snow Days: Jan: 6 days. Feb: 5 days. Mar: 1 days. Apr: 1 days. May: 0 days. Jun: 0 days. Jul: 0 days. Aug: 0 days. Sep: 0 days. Oct: 0 days. Nov: 1 days. Dec: 3 days.
Climate Trends
Average highs have stayed broadly stable across the available records. Average rainfall has remained broadly steady.
2016 to 2025
Avg high Avg rainfall
Climate summary
| Last 12 months | All years | |
|---|---|---|
| Hottest month | Jul 2025 · 31°C | Jul · 31°C |
| Coldest month | Jan 2025 · -7°C | Jan · -3°C |
| Wettest month | Jun 2025 · 211 mm | Apr · 134 mm |
| Windiest month | Mar 2025 · 23 km/h | Apr · 20 km/h |
Month-by-Month Weather Table
January
Poor 
February
Poor March
Fair April
Good May best
Excellent June best
Excellent July
Fair August best
Excellent September best
Excellent October best
Good November
Fair December
Poor | Month | Temp | Feels Like | Rain | Sun | Humidity | UV | Status | Details |
|---|---|---|---|---|---|---|---|---|
| January | 5°C / -3°C | 1°C / -8°C | 8days (78 mm) Wet | 5.6h Fair | 69% Muggy | 2.7 Moderate | Poor | View Details |
| February | 9°C / -2°C | 5°C / -6°C | 8days (71 mm) Wet | 7h Good | 66% Muggy | 3.7 Moderate | Poor | View Details |
| March | 15°C / 4°C | 12°C / 0°C | 12days (120 mm) Wet | 7.6h Good | 65% Muggy | 5.2 High | Fair | View Details |
| April | 19°C / 8°C | 18°C / 6°C | 11days (134 mm) Wet | 9h Good | 65% Muggy | 5.8 High | Good | View Details |
| May best | 24°C / 15°C | 25°C / 14°C | 14days (129 mm) Wet | 10h Excellent | 71% Muggy | 7.1 Very High | Excellent | View Details |
| June best | 30°C / 20°C | 33°C / 21°C | 10days (87 mm) Wet | 12h Excellent | 67% Muggy | 7.4 Very High | Excellent | View Details |
| July | 31°C / 22°C | 35°C / 25°C | 13days (107 mm) Wet | 12h Excellent | 71% Muggy | 7.5 Very High | Fair | View Details |
| August best | 30°C / 21°C | 33°C / 23°C | 10days (114 mm) Wet | 11h Excellent | 72% Muggy | 6.8 High | Excellent | View Details |
| September best | 28°C / 18°C | 29°C / 18°C | 7days (80 mm) Good | 10.2h Excellent | 68% Muggy | 5.9 High | Excellent | View Details |
| October best | 21°C / 11°C | 20°C / 9°C | 8days (84 mm) Wet | 7.9h Good | 66% Muggy | 4.3 Moderate | Good | View Details |
| November | 13°C / 4°C | 10°C / 1°C | 8days (70 mm) Wet | 6.9h Fair | 68% Muggy | 3 Moderate | Fair | View Details |
| December | 8°C / 0°C | 5°C / -4°C | 8days (64 mm) Wet | 5.7h Fair | 70% Muggy | 2.3 Moderate | Poor | View Details |
Compare Nearby City Climates
Frequently Asked Questions
The best months to visit Affton are May, June, August, September, October, when temperatures are comfortable and rainfall is at its lowest. This is based on 10-year climate averages for Affton, scoring temperature, rainfall, humidity, and sunshine hours.
The hottest month in Affton is July, with average daytime highs of 31°C (88°F). Plan outdoor activities for early morning or late afternoon if visiting during this period.
The coldest month in Affton is January, with average overnight lows of -3°C (26°F). Pack warm layers and expect shorter daylight hours during this period.
The wettest month in Affton is April, averaging 134mm of precipitation across 11 rainy days. An umbrella or waterproof jacket is essential.
The rainy season in Affton runs through May, July, March, April, with the heaviest rainfall in May. Based on 10-year averages for Affton.
Affton receives approximately 105 sunshine hours per year. The sunniest month is June with around 12 hours. Based on climate data for Affton.
The least favorable months to visit Affton are January, February, December, primarily due to very cold temperatures. For the best conditions, consider May, June, August, September, October instead.
The annual average UV index in Affton is 5, classified as moderate. Standard sun protection (sunscreen, hat) is recommended during prolonged outdoor exposure.
Average humidity in Affton is 68%, classified as moderate. Humidity levels are generally comfortable and should not affect outdoor activities for most people.
Yes, Affton receives snow. Months with snowfall average 3 snow days and 5 cm (2 in) of accumulation, with about 12 frost days during winter.
Average wind speeds in Affton are 17 km/h (11 mph). The windiest month is April with peak winds reaching 20 km/h (12 mph) (gusts up to 44 km/h / 28 mph).
Affton averages 5 clear-sky days per month with overall cloud cover around 56%. The clearest skies occur in October.
The annual average dew point in Affton is 9°C (48°F), which feels dry and comfortable. Outdoor activities are comfortable year-round from a humidity standpoint.
Affton has a Humid Subtropical climate, classified as Cfa 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 Affton ranges from 8°C (46°F) to 19°C (66°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 Affton. It earns a climate score of 7.8/10 with Excellent.
For June in Affton, pack Umbrella, Waterproof jacket, Breathable clothing, Sunscreen (SPF 30+), Sun hat. With average highs of 30°C (86°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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