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City of Johnston, IAJohnston, IA Weather Forecast
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Johnston Weather Forecast
| TONIGHT | MONDAY | MONDAY NIGHT | TUESDAY | TUESDAY NIGHT | WEDNESDAY | WEDNESDAY NIGHT | THURSDAY | THURSDAY NIGHT | FRIDAY | FRIDAY NIGHT | SATURDAY |
 |  | | | | | |  | | | |  |
| Chance of T-Storm | Chance of T-Storm | Chance of T-Storm | Chance of T-Storm | Chance of T-Storm | Chance of T-Storm | Chance of T-Storm | Showers | Chance of T-Storm | Chance of T-Storm | Chance of T-Storm | Chance of Showers |
| Lo: 59°FLo: 15°C | Hi: 79°FHi: 26°C | Lo: 69°FLo: 21°C | Hi: 71°FHi: 22°C | Lo: 59°FLo: 15°C | Hi: 71°FHi: 22°C | Lo: 65°FLo: 18°C | Hi: 75°FHi: 24°C | Lo: 65°FLo: 18°C | Hi: 75°FHi: 24°C | Lo: 65°FLo: 18°C | Hi: 75°FHi: 24°C |
| POP: 30% | POP: 70% | POP: 100% | POP: 90% | POP: 70% | POP: 90% | POP: 80% | POP: 70% | POP: 50% | POP: 60% | POP: 70% | POP: 50% |
POP = Probability of Precipitation.
Weather Outlook Updated: 424 PM CDT Sun Sep 13 2026 
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Issued: 639 PM CDT Sun Sep 13 2026
Key Messages
- Showers and thunderstorms across the area should diminish through the afternoon before storm chances return late tonight/early Monday morning.
- Severe thunderstorms and excessive rainfall are possible Monday afternoon and into the overnight hours. Heavy rainfall and training storms may result in flash flooding, particularly in cities and towns.
- Heavy rain and storm chances persist through at least the middle of the week, leading to both river flooding and flash flooding concerns.