September 2018 Weather in Yellowstone National Park — Graph
High & Low Weather Summary for September 2018
| Temperature | Humidity | Pressure | |
|---|---|---|---|
| High | 73 °F (Sep 5, 3:56 pm) | 97% (Sep 8, 7:56 am) | 30.40 "Hg (Sep 8, 7:56 am) |
| Low | 20 °F (Sep 26, 5:56 am) | 11% (Sep 17, 2:56 pm) | 29.80 "Hg (Sep 20, 3:56 am) |
| Average | 46 °F | 54% | 30.06 "Hg |
| * Reported Sep 1 12:56 am — Sep 30 11:56 pm, Yellowstone National Park. Weather by CustomWeather, © 2025 | |||
Note: Actual official high and low records may vary slightly from our data, if they occured in-between our weather recording intervals... More about our weather records
Yellowstone National Park Weather History for September 1, 2018
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| Conditions | Comfort | |||||||
|---|---|---|---|---|---|---|---|---|
| Time | Temp | Weather | Wind | Humidity | Barometer | Visibility | ||
| 12:56 am Sat, Sep 1 |  | 35 °F | Chilly. | 3 mph | ↑ | 85% | 30.06 "Hg | N/A |
| 1:56 am | | 34 °F | Chilly. | No wind | ↑ | 88% | 30.07 "Hg | N/A |
| 2:56 am | | 32 °F | Chilly. | 3 mph | ↑ | 92% | 30.06 "Hg | N/A |
| 3:56 am | | 32 °F | Chilly. | No wind | ↑ | 88% | 30.05 "Hg | N/A |
| 4:56 am | | 31 °F | Chilly. | 3 mph | ↑ | 92% | 30.05 "Hg | N/A |
| 5:56 am | | 30 °F | Chilly. | 3 mph | ↑ | 96% | 30.05 "Hg | N/A |
| 6:56 am | | 30 °F | Chilly. | No wind | ↑ | 92% | 30.06 "Hg | N/A |
| 7:56 am | | 34 °F | Chilly. | No wind | ↑ | 92% | 30.09 "Hg | N/A |
| 9:56 am | | 53 °F | Cool. | 5 mph | ↑ | 48% | 30.05 "Hg | N/A |
| 10:56 am | | 57 °F | Refreshingly cool. | No wind | ↑ | 44% | 30.03 "Hg | N/A |
| 11:56 am | | 61 °F | Refreshingly cool. | 12 mph | ↑ | 30% | 30.01 "Hg | N/A |
| 12:56 pm | | 61 °F | Refreshingly cool. | 7 mph | ↑ | 26% | 30.01 "Hg | N/A |
| 1:56 pm | | 63 °F | Mild. | 6 mph | ↑ | 27% | 30.00 "Hg | N/A |
| 2:56 pm | | 63 °F | Mild. | 8 mph | ↑ | 25% | 30.01 "Hg | N/A |
| 3:56 pm | | 64 °F | Mild. | N/A | ↑ | 24% | 30.01 "Hg | N/A |
| 4:56 pm | | 62 °F | Refreshingly cool. | 7 mph | ↑ | 20% | 30.02 "Hg | N/A |
| 5:56 pm | | 62 °F | Refreshingly cool. | 3 mph | ↑ | 20% | 30.03 "Hg | N/A |
| 6:56 pm | | 59 °F | Refreshingly cool. | No wind | ↑ | 21% | 30.04 "Hg | N/A |
| 7:56 pm | | 48 °F | Cool. | No wind | ↑ | 52% | 30.09 "Hg | N/A |
| 8:56 pm | | 42 °F | Quite cool. | No wind | ↑ | 62% | 30.09 "Hg | N/A |
| 9:56 pm | | 39 °F | Chilly. | No wind | ↑ | 67% | 30.08 "Hg | N/A |
| 10:56 pm | | 38 °F | Chilly. | No wind | ↑ | 70% | 30.06 "Hg | N/A |
| 11:56 pm | | 36 °F | Chilly. | No wind | ↑ | 75% | 30.07 "Hg | N/A |
| Weather by CustomWeather, © 2025 | ||||||||