Room-temperature limit
2 hours
1 hour above 90°F (32°C)
Overnight: discard
Food that sat out overnight has spent far longer than 2 hours in the danger zone (40–140°F).
Quick answer
Buttermilk left at room temperature for more than 2 hours (1 hour above 90°F / 32°C) should be thrown away. Bacteria multiply fastest between 40°F and 140°F, and reheating does not remove every toxin they make.
The verdict
Keep
Check it
Discard
Buttermilk left at room temperature for more than 2 hours (1 hour above 90°F / 32°C) should be thrown away. Bacteria multiply fastest between 40°F and 140°F, and reheating does not remove every toxin they make.
Danger zone°C
0 4 32 60 80
← FridgeHot holding →
Bacteria multiply fastest between 4 °C and 60 °C (40–140 °F).
How long buttermilk can sit out, by temperature
| Room temperature | Safe for | Then |
|---|---|---|
| Below 40°F (4°C) | Refrigerated — 1–2 weeks | Use within the fridge window |
| 40–90°F (4–32°C) | 2 hours | Discard |
| Above 90°F (32°C) | 1 hour | Discard |
| Overnight (8+ hours) | Not safe | Discard, even if reheated |
Store buttermilk safely next time
- Store on an inside shelf, not the door, at 40°F (4°C) or below.
- Close the container tightly; dairy absorbs fridge odours.
- Pour what you need and return it to the fridge right away.
More about buttermilk
FAQ
How long can buttermilk sit out?
No more than 2 hours at room temperature, or 1 hour above 90°F (32°C).
Is buttermilk left out overnight safe if I reheat it?
No. Some bacteria make heat-stable toxins that reheating does not destroy. If in doubt, throw it out.
What if buttermilk was left out for 3 hours?
Past the 2-hour mark, discard it, even if it looks and smells fine.
How long does buttermilk last in the fridge?
1–2 weeks at 40°F (4°C) or below, if refrigerated promptly.
Numbers on this page come from USDA FoodKeeper and FSIS guidance. Last verified November 2026. How we verify our data · Report a wrong number