JACKSON, Wyo. – Teton County picked up some much-needed moisture in mid-September. A stretch of perfect fall weather has taken hold in late September and will continue into early October with sunny skies, warm days, chilly nights, and changing leaves.
Recent Weather Conditions
The first nine days of September were warm and dry, and often smoky, as wildfires continued to burn across the region.
In mid-September, a series of low pressure systems brought welcome rainfall to the Tetons, along with snow across the higher terrain.
The town of Jackson received 1.37 inches of rain between September 10 and 19, while precipitation totals up high included 2.37 inches at Jackson Hole Mountain Resort (Raymer Plot) and 3.60 inches at Grand Targhee.
Chilly air arrived with the system on September 17-18 with 3-4 inches of snow reported between 9,000 and 10,000 feet. The high temperature in Jackson only hit 50ºF on September 17, making it the coolest day since May 23.
The mid-September systems put a serious damper on fire activity locally and regionally, and since September 20, we have enjoyed ideal conditions with blue skies and comfortable temperatures.
The combination of high pressure, dry air, and longer nights at this time of year have resulted in impressive morning vs. afternoon temperature swings. For example, on Wednesday, we started out with a low of 32ºF in Jackson and so far we have a high of 82ºF – nearly a 50-degree difference!
Upcoming Weather Pattern
This wonderful stretch of fall weather will continue through the end of September and into early October. High pressure will remain the dominant pattern across the Western U.S., but we are well beyond the heat of the summer so temperatures will continue to be quite comfortable.
Rain chances will be minimal over the next seven days, with only a slight chance that we get brushed by a system moving into the Pacific Northwest around the middle of next week.
Temperature-wise, warm days and cool nights will continue to be the norm with slight day-to-day fluctuations. After topping 80ºF on Wednesday, temperatures will be slightly cooler on Thursday and Friday, before approaching 80ºF again on Saturday and Sunday.
Average highs in Jackson at this time of year are in the upper 60s, so high temperatures will be well above average for the end of September. However, lows will be close to average as temperatures drop to around freezing in Jackson on most mornings.
Looking further out, temperatures may cool off a little bit late next week and into the first weekend of October in response to low pressure troughs moving into the Pacific Northwest, but meaningful precipitation chances look marginal in our area at this time.
Alan Smith, Meteorologist
