St. Marys, IA Weather & Growing Conditions
Today
85°F
Chance Showers And Thunderstorms
A chance of showers and thunderstorms after 10am. Partly sunny. High near 85, with temperatures falling to around 83 in the afternoon. West wind 6 to 9 mph. Chance of precipitation is 40%. New rainfall amounts less than a tenth of an inch possible.
7-day forecast
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Today | 85°F | Chance Showers And Thunderstorms | 6 to 9 mph W | 39% |
| Tonight | 64°F | Showers And Thunderstorms | 6 to 12 mph NNE | 90% |
| Wednesday | 72°F | Showers And Thunderstorms Likely | 8 mph NNE | 68% |
| Wednesday Night | 59°F | Chance Showers And Thunderstorms | 2 to 7 mph NE | 41% |
| Thursday | 80°F | Mostly Sunny | 5 mph ENE | 8% |
| Thursday Night | 62°F | Mostly Clear | 5 mph SE | 5% |
| Friday | 85°F | Sunny | 3 to 7 mph S | 5% |
| Friday Night | 67°F | Mostly Clear | 7 mph S | 10% |
| Saturday | 89°F | Sunny | 5 to 12 mph SSW | 5% |
| Saturday Night | 73°F | Mostly Clear | 10 to 15 mph SSW | 10% |
| Sunday | 90°F | Mostly Sunny | 14 mph SSW | 10% |
| Sunday Night | 73°F | Slight Chance Showers And Thunderstorms | 14 mph S | 24% |
| Monday | 91°F | Slight Chance Showers And Thunderstorms then Mostly Sunny | 15 mph SSW | 24% |
| Monday Night | 73°F | Chance Showers And Thunderstorms | 15 mph SSE | 26% |
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 Aug 4, 2026.