JACKSON, Wyo. – August was a wet and stormy month across Teton County as moisture from the North American monsoon frequently invaded the area. In fact, August 2022 will go down as the second wettest August on record in the Town of Jackson. September is starting out on a much drier note with record-challenging warmth also expected early in the month.
August 2022 Review
August was much wetter than average and also warmer than average across Teton County thanks to an active North American Monsoon. Thunderstorms were a common occurrence across Wyoming, often developing each afternoon for days on end.
The Town of Jackson received an impressive 3.65 inches of rain during August, making this the second wettest August on record. Jackson ended up falling just short of the all-time August rainfall record of 3.80 inches, set in 1945.
The historical August rainfall average in Jackson is 1.23 inches, so rainfall in August 2022 was nearly triple that of average.
Elsewhere across Teton County, Moran received 2.90 inches of rain (fifth wettest August on record) and Alta received 3.02 inches of rain (seventh wettest August on record). For Teton County as a whole, this was the 10th wettest August on record, which factors in model-estimated rainfall totals across the higher elevations.
Jackson received measurable rainfall on 15 days in August. The highest 24-hour total was 0.86 inches for the 24-hour period ending at 9 a.m. on August 14. More impressively, most of this rain fell in less than one hour. Also, Jackson recorded impressive 24-hour rain totals on August 6 (0.80 inches) and August 7 (0.74 inches).
Overall, August 2022 was the wettest month in the Town of Jackson since February 2017 when 5.75 inches of precipitation was recorded.
This was not one of the wettest months in recent years across the higher elevations, though, as there is a greater difference between mountain and valley precipitation during the colder months compared to the summer months when rainfall is more driven by atmospheric instability and is less elevation-dependent.
During the summer months, we typically hope to receive enough rainfall to prevent drought conditions from worsening since evaporation rates are highest during the summer. However, we received enough rain this August to result in an improvement in drought conditions overall.
Most of Teton County remains in a Level 2-Severe Drought, but this is an improvement compared to where we were in July. Most of Yellowstone remains drought-free as well, though just barely with “abnormally dry” conditions noted.
Despite being a wet month, temperatures were also well above average across Teton County in August. The moisture we received in August was subtropical in nature and we did not see any significant cold fronts, though cloud cover did result in a few refreshingly cool days.
High temperatures in August were cooler than July, and only a little bit above the long-term average. Frequent afternoon thunderstorms and rainfall made for some comfortable afternoons and evenings compared to the previous month.
The average high in Jackson during August 2022 was 82.7ºF, which is 1.6ºF above the long-term average. High temperatures ranged from 68ºF on August 7 to 92ºF on August 2.
Low temperatures in August were unseasonably warm due in a large part to the continual presence of monsoonal moisture, which prevented nighttime temperatures from dropping too much.
The average low in Jackson during August 2022 was 46.5ºF, which is 6.9ºF above the long-term average. Low temperatures ranged from 37ºF on August 29 and 30 to 60ºF on August 11.
The low temperature dropped below 40ºF on only two occasions, and not until August 29, both of which are quite unusual. On the flip side, there were eight days with a low temperature of 50ºF or higher.
The average temperature (factoring in both the high and the low temperatures) was 4.3 degrees warmer than normal in the Town of Jackson in August 2022.
Monthly Temperatures for Jackson (Water Year to Date Since October):
| Month | Avg High | Avg Low | Departure | Highest | Lowest |
| October | 56.5 | 29.0 | + 1.7 | 73 | 18 |
| November | 46.3 | 24.0 | + 7.4 | 59 | 6 |
| December | 35.3 | 21.0 | + 10.2 | 58 | -6 |
| January | 22.7 | -3.3 | – 7.0 | 42 | -19 |
| February | 29.9 | 3.0 | – 4.8 | 46 | -16 |
| March | 45.3 | 18.3 | + 0.8 | 66 | -15 |
| April | 46.0 | 24.1 | – 4.6 | 64 | 1 |
| May | 57.2 | 33.0 | – 2.6 | 79 | 18 |
| June | 71.2 | 38.6 | – 0.5 | 86 | 29 |
| July | 85.8 | 42.3 | + 2.2 | 93 | 35 |
| August | 82.7 | 46.5 | + 4.3 | 92 | 37 |
| Water YTD | + 0.6 |
Monthly Precipitation for Jackson (Water Year to Date Since October):
| Month | Precipitation | Departure | Days of Precip | Snowfall | Departure |
| October | 1.71″ | + 0.30″ | 10 | 0.5″ | – 1.5″ |
| November | 1.35″ | – 0.36″ | 6 | 0.7″ | – 10.8″ |
| December | 1.83″ | + 0.19″ | 18 | 26.6″ | + 8.5″ |
| January | 1.23″ | – 0.05″ | 8 | 15.1″ | – 3.9″ |
| February | 0.29″ | – 0.89″ | 4 | 5.1″ | – 8.5″ |
| March | 0.66″ | – 0.60″ | 8 | 10.0″ | + 2.3″ |
| April | 1.95″ | + 0.65″ | 13 | 17.2″ | + 14.5″ |
| May | 2.19″ | – 0.01″ | 16 | 1.1″ | + 0.5″ |
| June | 1.58″ | + 0.08″ | 10 | 0.0″ | – |
| July | 0.06″ | – 1.06″ | 4 | 0.0″ | – |
| August | 3.65″ | + 2.42″ | 15 | 0.0″ | – |
| Water YTD | 16.50″ | + 0.67″ | 112 | 76.3″ | + 1.1″ |
September 2022 Outlook
September is shaping up to be a warmer and drier than average month across Teton County and Western Wyoming. The monsoon has weakened significantly and shifted well to the south, while high pressure is dominating the pattern across the Western U.S. early this month.
In fact, high temperatures will be approaching record levels each day from Friday through Wednesday, including the potential for multiple days with 90+ degree highs in Jackson. The all-time record high for September in Jackson is 93ºF, and it’s not totally out of the question we could reach this record, though current forecasts are in the 88-92º range over the next six days.
Cooler temperatures are expected to arrive late next week and we should see more seasonal temperatures thereafter, but overall, a warmer than average month is expected.
Rain chances are also looking limited early this month and possibly even into mid-month, though some shower chances should occasionally return to the picture starting as early as the second half of next week.
During the second half of the month, rain chances should be higher as we typically start to see our first chilly fall low pressure systems around this time of year. The higher elevations typically start to see snow during September as well, with the odds of this increasing over the second half of the month especially.
In terms of fire danger, we are seeing somewhat of an increase early this month due to unseasonably hot temperatures. But overall, September is not expected to be a particularly active fire month in Western Wyoming due to abundant August rain, along with the seasonal decrease in temperatures that will eventually get underway.
September is a wonderful month in Jackson Hole with multi-day stretches of dry and sunny days common in between low pressure systems, along with comfortable temperatures that are (usually) not too hot and not too cold. Also, September is fall color season around here, with peak color typically occurring during the final week of the month.
Thunderstorms are still possible in September, but less common compared to June, July and August. Now that the monsoon has relented across this part of the West, thunderstorms usually occur at the leading edge of a disturbance or frontal system.
In terms of historical averages for Jackson, the average high in September is 71.5ºF and the average low is 32.3ºF. Sub-freezing overnight lows are common during clear and calm nights by this time of year. Average rainfall in September is 1.60 inches, but the total number of rainy days in September is relatively low in most years.
The Town of Jackson does not average any accumulating snowfall in September, but it can happen (and did happen as recently as two years ago). Typically, when snow does fall in the valley in September, it happens late in the month and struggles to accumulate.
Alan Smith, Meteorologist
