St. Marys, IA Weather & Growing Conditions
Today
82°F
Chance Showers And Thunderstorms
A chance of showers and thunderstorms. Partly sunny. High near 82, with temperatures falling to around 80 in the afternoon. West southwest wind 5 to 9 mph. Chance of precipitation is 50%. New rainfall amounts between a tenth and quarter of an inch possible.
7-day forecast
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Today | 82°F | Chance Showers And Thunderstorms | 5 to 9 mph WSW | 47% |
| Tonight | 62°F | Chance Showers And Thunderstorms | 9 mph N | 51% |
| Sunday | 66°F | Chance Rain Showers then Slight Chance Showers And Thunderstorms | 12 mph NNE | 43% |
| Sunday Night | 56°F | Chance Showers And Thunderstorms then Showers And Thunderstorms Likely | 13 mph NE | 62% |
| Monday | 61°F | Rain Showers Likely | 13 mph NE | 62% |
| Monday Night | 52°F | Rain Showers Likely | 10 mph NE | 58% |
| Tuesday | 60°F | Partly Sunny | 9 mph NE | 13% |
| Tuesday Night | 47°F | Partly Cloudy | 3 to 7 mph ENE | 4% |
| Wednesday | 63°F | Sunny | 6 mph ENE | 2% |
| Wednesday Night | 52°F | Partly Cloudy | 3 mph E | 4% |
| Thursday | 66°F | Slight Chance Rain Showers | 5 mph ESE | 22% |
| Thursday Night | 56°F | Mostly Cloudy | 5 mph ESE | 9% |
| Friday | 67°F | Partly Sunny | 2 to 6 mph ESE | 11% |
| Friday Night | 57°F | Mostly Cloudy | 5 mph ESE | 9% |
Forecast source: National Weather Service (api.weather.gov). Updated through the day.
Growing snapshot for St. Marys, IA
Last spring frost
Apr 24
First fall frost
Oct 12
Growing season
168 days
Hardiness zone
5b
Explore more for St. Marys, IA: full frost dates · planting calendar · Iowa frost dates
Climate data from the nearest NOAA station, Indianola 2W, Ia (6 mi). Frost dates are 1991–2020 averages, not a forecast. Page updated Sep 19, 2026.