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Costello School Weather Forecast
| REST OF TONIGHT | THURSDAY | THURSDAY NIGHT | FRIDAY | FRIDAY NIGHT | SATURDAY | SATURDAY NIGHT | SUNDAY | SUNDAY NIGHT | MONDAY | MONDAY NIGHT | TUESDAY |
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| Chance of Rain | Chance of Rain | Chance of Snow | Rain and Snow | Partly Cloudy | Partly Cloudy | Mostly Clear | Partly Cloudy | Partly Cloudy | Partly Cloudy | Mostly Clear | Mostly Sunny |
| Lo: 39°FLo: 4°C | Hi: 45°FHi: 7°C | Lo: 31°FLo: -1°C | Hi: 41°FHi: 5°C | Lo: 31°FLo: -1°C | Hi: 45°FHi: 7°C | Lo: 31°FLo: -1°C | Hi: 49°FHi: 9°C | Lo: 31°FLo: -1°C | Hi: 49°FHi: 9°C | Lo: 31°FLo: -1°C | Hi: 51°FHi: 11°C |
| POP: 20% | POP: 90% | POP: 70% | POP: 50% |
POP = Probability of Precipitation.
Weather Outlook Updated: 905 PM CST Wed Nov 11 2026 
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Issued: 1106 PM CST Wed Nov 11 2026
Key Messages
- A prolonged period of lake effect rain showers (mixed with and possibly changing over to snow at times) is expected Thursday through early Saturday, primarily in northwest Indiana.
- There is growing concern for several inches of slushy snow accumulation Thursday night into Friday morning near the Illinois and Indiana border (southern Cook, eastern Will, western Lake IN) including during the Friday morning commute.
- Cooler temperatures are expected late this week into this weekend befor...