Affton, Missouri Weather
Fireflies pulse through the magnolias. Day 77 of spring. Read this microseason across nine climate regions →
Affton weather forecast — hour by hour, 7-day outlook, NOAA radar
- TodayJun 3Clear——82°55°—
- ThursdayJun 4Overcast——89°61°+7°
- FridayJun 5Overcast13%—86°67°-3°
- SaturdayJun 6Light Drizzle17%—93°67°+7°
- SundayJun 7Heavy Showers51%1.8″83°71°-10°
- MondayJun 8Showers64%0.04″80°70°-3°
- TuesdayJun 9Thunderstorm40%—93°69°+13°
Ozone at AQI 40. AQI down 10 over the last 6 hours (steady decline since this morning). Overcast through the UV peak window (cloud cover ~100%) — afternoon ozone should stay flat.
OK No precautions needed for the general population; unusually sensitive individuals may consider limiting prolonged outdoor exertion during the projected peak around 6 AM.
What's driving it
Ozone × UV × Sky
Ozone at AQI 40. Overcast through the UV peak window (cloud cover ~100%) — afternoon ozone should stay flat.
- Present
- AQI 40
- UV peak
- 0.0 at 1 PM
- Sky at peak
- overcast
- Projected peak
- AQI 5
Trends
Seven days of AQI and PM2.5.
Hourly air-quality data from the Copernicus Atmosphere Monitoring Service, charted across the past and next several days. Dashed lines mark the AQI breakpoints at 50 (Good → Moderate) and 100 (Moderate → Unhealthy for Sensitive Groups).
A summer fog for fair, a winter fog for rain.
- Moonrise
- 4:26 AM
- Moonset
- 2:07 PM
- In sign
- ♑︎ Capricorn
Fireflies pulse through the magnolias
Affton at a glance
- Today vs. normal: 9°F below the seasonal normal for this latitude
- Last frost: April 7 (climatological average for this latitude)
- Microseason: Jun 1–5
- Planting window: Harvest spring lettuce before it bolts. Sow heat-tolerant greens.
Right now in the garden
Peak growing season
As of June 4, the growing season is at its peak — frost is months away. Continue succession-planting beans and summer squash. Start fall brassicas (broccoli, cabbage, kale) from seed indoors for transplanting in late summer.
SPC Convective Outlook
Storm Prediction Center — Affton
SPC has placed Affton in the General Thunderstorms category for severe thunderstorms day after tomorrow.
- TODAYNONENo severe risk
- TOMORROWNONENo severe risk
- DAY 3TSTMGeneral Thunderstorms
Thunderstorms possible. Not severe, but capable of producing lightning and brief heavy rain.
Source: NOAA / NWS Storm Prediction Center categorical convective outlook. Outlooks are re-issued multiple times per day; this page reflects the most recent SPC polygons covering the city’s coordinates.
Planting calendar
| Month | Plant | Harvest |
|---|---|---|
| January | — | — |
| February | — | — |
| March | — | — |
| April | lettuce, peas, spinach, radishes | — |
| May | lettuce, peas, spinach, radishes, tomatoes, peppers, beans, squash | lettuce, peas, radishes |
| June | tomatoes, peppers, beans, squash | lettuce, peas, radishes |
| July | tomatoes, peppers, beans, squash | tomatoes, beans, summer squash |
| August | — | tomatoes, beans, summer squash |
| September | fall brassicas, garlic (overwinter), carrots | tomatoes, beans, summer squash |
| October | fall brassicas, garlic (overwinter), carrots | winter squash, tomatoes (last) |
| November | — | — |
| December | — | — |
A year in weather
Affton's warmest month is July (~81°F mean) and its coldest is January (~33°F). Rainfall peaks in May (4.9 inches) and bottoms out in February (2.3 inches).
| Month | Mean temp | Precip | Rainy days |
|---|---|---|---|
| January | 33° | 2.7″ | 9 |
| February | 37° | 2.3″ | 8 |
| March | 47° | 3.6″ | 12 |
| April | 58° | 4.8″ | 16 |
| May | 68° | 4.9″ | 16 |
| June | 77° | 4.7″ | 16 |
| July | 81° | 4.2″ | 14 |
| August | 79° | 3.8″ | 13 |
| September | 72° | 3.4″ | 11 |
| October | 60° | 3.2″ | 11 |
| November | 48° | 3.7″ | 12 |
| December | 37° | 2.6″ | 9 |
Regional context
Affton's baseline climate, derived from NOAA NCEI 1991-2020 normals at the nearest reporting station, swings from a January mean of 33°F to a July mean of 81°F — a 48°F seasonal arc typical of the mid-latitude bands. Annual precipitation runs about 43.9 inches spread across roughly 147 days with measurable rain or snow each year.
Precipitation runs summer-dominant here: May averages 4.9 inches across 16.0 days with measurable rain, driven mostly by warm-season storms and thunderstorm activity, while February drops to just 2.3 inches across 8.0 rainy days under drier cool-season air. That wet-warm-summer pattern groups Affton with places like Lakeshire, MO, Wilbur Park, MO and St. George, MO — a regional cohort where summer thunderstorm season carries more than half the annual moisture.
The frost-sensitive growing window opens around mid-April, when overnight lows reliably clear freezing for cool-season crops like peas, lettuce, spinach, and radishes. Warm-season transplants — tomatoes, peppers, and basil — typically wait two weeks past that date to avoid late spring cold snaps. The window closes around mid-November, when overnight lows resume dipping below freezing and frost-tender plants need protection or harvest. The dates above are 1991-2020 normals; in a given year either bookend can move 1-2 weeks either direction. Within Affton, low-lying parcels along drainage features typically lose 4-7°F of overnight low temperature versus the bench positions on calm clear nights, which shifts the working last-frost date by a week or more.
Similar climates: Lakeshire, MO, Wilbur Park, MO, St. George, MO, Marlborough, MO, Grantwood Village, MO.
Frequently asked
- When does it freeze in Affton?
- Affton's last spring frost typically falls around mid-April, and the first fall frost arrives around mid-November.
- What is the rainy season in Affton?
- May is the wettest month with about 4.9 inches of rain on average; the city receives roughly 44 inches annually.
- What is the warmest month in Affton?
- July is typically warmest, averaging about 81°F.
- What is the coldest month in Affton?
- January is typically coldest, averaging about 33°F.
- When can I start a vegetable garden in Affton?
- Cool-season crops (peas, lettuce) can be sown around the last spring frost (mid-April); warm-season crops (tomatoes, peppers) wait until 1–2 weeks after.
- How many rainy days does Affton get?
- Affton averages about 147 rainy days per year.
- What hardiness zone is Affton?
- Affton'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
Affton, Missouri sits in a humid subtropical climate zone. January means hover near 33°F while July averages 81°F — a 48°F seasonal swing.
Across the year, Affton receives about 44 inches of precipitation spread over roughly 147 rainy days.
The rhythm of the year is set by latitude (38.5°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.