St. Marys, Iowa Weather
Cicadas claim the afternoon. Day 15 of summer. Read this microseason across nine climate regions →
St. Marys weather forecast — hour by hour, 7-day outlook, NOAA radar
- TodayJul 4Light Drizzle66%0.01″85°70°—
- SundayJul 5Overcast12%—88°68°+3°
- MondayJul 6Light Drizzle——91°68°+3°
- TuesdayJul 7Overcast——85°65°-6°
- WednesdayJul 8T-storm w/ Hail36%—88°66°+3°
- ThursdayJul 9Light Showers48%0.02″79°67°-9°
- FridayJul 10Partly Cloudy27%—83°66°+4°
AQI 40 (Good), driven by PM2.5. AQI up 9 over the last 6 hours (gradual rise). PM2.5 at 7.2 µg/m³ (AQI 40) with a 0.89 fine-to-coarse ratio and 3 mph wind — combustion smoke trapped in calm air, not road dust.
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 30 now. With UV 0.0 peaking around 1 PM under clear skies, surface ozone likely climbs to AQI 7 around 1 PM.
- Present
- AQI 30
- UV peak
- 0.0 at 1 PM
- Sky at peak
- clear
- Projected peak
- AQI 7
PM × Wind × Precip
PM2.5 at 7.2 µg/m³ (AQI 40) with a 0.89 fine-to-coarse ratio and 3 mph wind — combustion smoke trapped in calm air, not road dust.
- PM2.5/PM10
- 0.89
- Wind
- calm
- Recent rain
- 0h in last 6h
- Pattern
- stagnant smoke
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).
If the first of July be rainy weather, 'twill rain more or less for four weeks together.
- Moonrise
- 11:34 PM
- Moonset
- 11:27 AM
- In sign
- ♓︎ Pisces
Cicadas claim the afternoon
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: Jul 1–5
- Planting window: Harvest early potatoes. Begin drying onions on the surface.
16-Day Forecast — St. Marys
- Sat85°70°66%
- Sun88°68°12%
- Mon91°68°1%
- Tue85°65°1%
- Wed88°66°36%
- Thu79°67°48%
- Fri83°66°27%
- Sat76°63°8%
- Sun77°60°9%
- Mon82°61°4%
- Tue87°68°7%
- Wed85°68°9%
- Thu88°71°19%
- Fri92°71°14%
- Sat92°75°19%
- Sun84°66°13%
Forecast data from Open-Meteo (CC BY 4.0).
Right now in the garden
Peak growing season
As of July 5, 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 includes St. Marys in the general thunderstorm area today — no severe risk, but storms are possible.
- TODAYTSTMGeneral Thunderstorms
- TOMORROWTSTMGeneral Thunderstorms
- DAY 3NONENo severe risk
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.
ZIP codes in St. Marys
- 50241