Rock Springs weather in September: Rock Springs, Wyoming: normal highs, lows, rain and records for September
Rock Springs in September has a normal high of 71°F and a normal low of 44°F, a daily mean of 57°F, falling from 77°F on the 1st to 64°F by the 30th. Measurable precipitation falls on 6 days in a normal September, 0.79 inches in all. (NOAA 1991-2020 normals)
In metric: a normal high of 22°C and low of 7°C, 20 mm of precipitation and 3 cm of snow in September.
- NOAA stationRock Springs Airport
- Station IDUSW00024027
- Location41.59°N 109.05°W
- Elevation6,741 ft (2,055 m)
- Population22,967
- Jan 30° 14°
- Feb 33° 16°
- Mar 44° 24°
- Apr 53° 30°
- May 63° 38°
- Jun 75° 47°
- Jul 84° 55°
- Aug 82° 53°
- Sep 71° 44°
- Oct 56° 33°
- Nov 41° 22°
- Dec 30° 13°
Each month: normal high (large) and low, °F. Fill: the month's normal mean, colder blue to hotter red.
How warm is Rock Springs in September?
The normal high is 71°F and the normal low 44°F, for a daily mean of 57.3°F. September is 10.0°F cooler than August and 12.8°F warmer than October. September is the 4th warmest month of the year in Rock Springs and the 4th wettest. Across the month the normal high falls 13°F, from 77°F on September 1 to 64°F on September 30. From one year to the next September's mean temperature typically moves about 2.3°F either way (NOAA's standard deviation), so roughly two Septembers in three average between 55°F and 60°F.
Bars above: each day's normal high to low. Columns below: the chance of 0.01 inch or more of precipitation that day, on a scale of 0 to 100% (highest 21%).
| Day | High | Low | Chance of 0.01 in | Chance of 0.10 in |
|---|---|---|---|---|
| September 1 | 77°F | 49°F | 20% | 7% |
| September 8 | 74°F | 47°F | 20% | 8% |
| September 15 | 71°F | 44°F | 21% | 8% |
| September 22 | 68°F | 42°F | 21% | 8% |
| September 30 | 64°F | 39°F | 20% | 8% |
Every day of September: normal high, low and chance of precipitation (warmest afternoon September 1, coldest night September 30)
| Day | High | Low | Chance of 0.01 in | Chance of 0.10 in | Daylight |
|---|---|---|---|---|---|
| September 1 | 77°F | 49°F | 20% | 7% | 13 h 10 min |
| September 2 | 76°F | 49°F | 20% | 7% | 13 h 10 min |
| September 3 | 76°F | 48°F | 20% | 7% | 13 h 10 min |
| September 4 | 76°F | 48°F | 20% | 7% | 13 h |
| September 5 | 75°F | 48°F | 20% | 8% | 13 h |
| September 6 | 75°F | 47°F | 20% | 8% | 13 h |
| September 7 | 74°F | 47°F | 20% | 8% | 12 h 50 min |
| September 8 | 74°F | 47°F | 20% | 8% | 12 h 50 min |
| September 9 | 74°F | 46°F | 20% | 8% | 12 h 50 min |
| September 10 | 73°F | 46°F | 20% | 8% | 12 h 50 min |
| September 11 | 73°F | 46°F | 20% | 8% | 12 h 40 min |
| September 12 | 72°F | 45°F | 21% | 8% | 12 h 40 min |
| September 13 | 72°F | 45°F | 21% | 8% | 12 h 40 min |
| September 14 | 72°F | 45°F | 21% | 8% | 12 h 40 min |
| September 15 | 71°F | 44°F | 21% | 8% | 12 h 30 min |
| September 16 | 71°F | 44°F | 21% | 8% | 12 h 30 min |
| September 17 | 70°F | 44°F | 21% | 8% | 12 h 30 min |
| September 18 | 70°F | 43°F | 21% | 8% | 12 h 20 min |
| September 19 | 69°F | 43°F | 21% | 8% | 12 h 20 min |
| September 20 | 69°F | 42°F | 21% | 8% | 12 h 20 min |
| September 21 | 68°F | 42°F | 21% | 8% | 12 h 20 min |
| September 22 | 68°F | 42°F | 21% | 8% | 12 h 10 min |
| September 23 | 67°F | 41°F | 21% | 8% | 12 h 10 min |
| September 24 | 67°F | 41°F | 20% | 8% | 12 h 10 min |
| September 25 | 67°F | 41°F | 20% | 8% | 12 h 10 min |
| September 26 | 66°F | 40°F | 20% | 8% | 12 h |
| September 27 | 66°F | 40°F | 20% | 8% | 12 h |
| September 28 | 65°F | 39°F | 20% | 8% | 12 h |
| September 29 | 65°F | 39°F | 20% | 8% | 11 h 50 min |
| September 30 | 64°F | 39°F | 20% | 8% | 11 h 50 min |
- Normal high
- 71°FSeptember average
- Normal low
- 44°FSeptember average
- Precipitation
- 0.79 inmonth total
- Days with precipitation
- 60.01 inch or more
- Snowfall
- 1.2 inmonth total
- Nights at 32°F or colder
- 2
- Daylight
- 13 h 10 min to 11 h 50 minSeptember 1 to September 30
- Days at 70°F or more
- 19
- Days at 80°F or more
- 6
- Sunshine
- 86%of clear-sky sunlight (NASA)
Source: NOAA NCEI 1991-2020 daily normals, station USW00024027; monthly normals. Daylight is computed from the place's latitude with NOAA's solar equations.
Does it rain or snow in Rock Springs in September?
On a given September day the chance of 0.01 inch or more is 20% on average, highest around September 17 (21%). In all, 0.79 in falls on 6 days of a normal September.
In a normal September in Rock Springs, 2 nights fall to freezing and snowfall averages 1.2 inches.
Source: NOAA NCEI 1991-2020 daily and monthly normals, station USW00024027.
How humid and windy is Rock Springs in September?
At 3 p.m. the normal temperature is 63°F with 25% relative humidity and a dew point of 26°F; at 6 a.m. it is 41°F with 58% humidity. The wind averages 10.0 mph, most often from the west-southwest in the afternoon. A dew point under 50°F feels dry.
| Time | Temperature | Dew point | Humidity | Wind | Clear or few clouds |
|---|---|---|---|---|---|
| 6 a.m. | 41°F | 28°F | 58% | 7.3 mph | 78% |
| 9 a.m. | 49°F | 30°F | 47% | 8.6 mph | 79% |
| noon | 59°F | 29°F | 31% | 12.2 mph | 75% |
| 3 p.m. | 63°F | 26°F | 25% | 14.3 mph | 69% |
| 6 p.m. | 57°F | 26°F | 30% | 11.4 mph | 73% |
| 9 p.m. | 50°F | 27°F | 41% | 10.0 mph | 77% |
Source: NOAA NCEI 1991-2020 hourly normals, station USW00024027. Hourly normals exist only for NOAA's first-order stations; a dash where NOAA publishes no value for that hour (the sky at some hours).
What are the records for September in Rock Springs?
The warmest September temperature on this station's record (since 1948) is 93°F, on September 7, 2022; the coldest is 5°F, on September 18, 1965. The wettest September brought 3.67 in (1965); the snowiest, 22.4 inches (1965).
The September mean against the 1991-2020 normal of 57.3°F: 2021 59.3°F (+2.0), 2022 62.3°F (+5.0), 2023 59.4°F (+2.1), 2024 61.8°F (+4.5), 2025 60.0°F (+2.7), 2026 61.0°F (+3.7). 6 of 6 ran warmer than normal.
| September | Mean | Against normal | Precip. |
|---|---|---|---|
| 2021 | 59.3°F | +2.0°F | 0.37 in |
| 2022 | 62.3°F | +5.0°F | 0.62 in |
| 2023 | 59.4°F | +2.1°F | 0.74 in |
| 2024 | 61.8°F | +4.5°F | 0.39 in |
| 2025 | 60.0°F | +2.7°F | 0.54 in |
| 2026 | 61.0°F | +3.7°F | 0.31 in |
Source: records: ACIS, station USW00024027; recent months: ACIS, station USW00024027. Records and recent months use complete months only.
How does September in Rock Springs compare across Wyoming?
Across the 71 places PlainClimate covers in Wyoming, September normal highs run from 65°F in Sundance to 81°F in Yoder; Rock Springs's is 71°F.
Source: NOAA NCEI 1991-2020 monthly normals for every station in the state.
Other months and places
- Rock Springs in August82°F by day, 53°F at night
- Rock Springs in October56°F by day, 33°F at night
- Rock Springs through the yearEvery month, frost dates, records and recent years
- Wyoming in SeptemberThe statewide normal and the warmest and coolest places
- Yoder: Wyoming's warmest Septembernormal high 81°F