St. Marys, IA Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for St. Marys, a city in Warren County, Iowa.
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 for St. Marys
| 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) for St. Marys (41.308, -93.734). Updated through the day.
Growing snapshot for St. Marys
Last spring frost
Apr 24
First fall frost
Oct 12
Growing season
168 days
Hardiness zone
5b
More local growing data for St. Marys: nearby ZIP 50241 weather · frost dates · planting calendar · Iowa frost dates
Nearby towns & communities
Ackworth
Carlisle
Hartford
Indianola
Lacona
Martensdale
Milo
New Virginia
Norwalk
Sandyville
Spring Hill
Climate data from the nearest NOAA station, Indianola 2W, Ia (6 mi from St. Marys). Frost dates are 1991–2020 averages, not a forecast. Page updated Aug 4, 2026.