St. Marys, Iowa Weather
Prairie lightning bugs rise. Day 76 of spring. Read this microseason across nine climate regions →
St. Marys weather forecast — hour by hour, 7-day outlook, NOAA radar
- TodayJun 3Partly Cloudy——82°58°—
- ThursdayJun 4Drizzle34%0.06″85°64°+3°
- FridayJun 5Thunderstorm73%0.43″85°66°0°
- SaturdayJun 6Heavy Showers61%—83°63°-2°
- SundayJun 7Showers55%—83°68°0°
- MondayJun 8Showers54%—79°67°-4°
- TuesdayJun 9Drizzle17%—82°69°+3°
Ozone at AQI 75 — peak already passed at 1 PM under clear skies. AQI up 16 in the last 6 hours — air quality is degrading. Levels should ease through evening.
OK No precautions needed for the general population; unusually sensitive individuals may consider limiting prolonged outdoor exertion.
What's driving it
Ozone × UV × Sky
Ozone at AQI 75 — peak already passed at 1 PM under clear skies. Levels should ease through evening.
- Present
- AQI 75
- UV peak
- 4.7 at earlier today
- Sky at peak
- clear
- Projected peak
- AQI 75
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).
The higher the clouds, the finer the weather.
- Moonrise
- 4:12 AM
- Moonset
- 1:09 PM
- In sign
- ♑︎ Capricorn
Prairie lightning bugs rise
St. Marys at a glance
- Today vs. normal: 8°F above the seasonal normal for this latitude
- Last frost: April 24 (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 3, 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 — St. Marys
SPC has placed St. Marys in the Slight Risk category for severe thunderstorms day after tomorrow.
- TODAYNONENo severe risk
- TOMORROWMRGLMarginal Risk
- DAY 3SLGTSlight Risk
Scattered severe storms possible. A few tornadoes, hail, and damaging wind gusts possible.
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.