JACKSON, Wyo. – June has been an active month weather-wise across Wyoming with above-average rainfall statewide through the first three weeks of the month. In the Town of Jackson, we are on pace to see the wettest June since 2010.
June 2023 Rainfall So Far
The first three weeks of June have featured a consistent south-to-southwest flow across Wyoming, which has transported and reinforced Pacific moisture into our region. Gulf of Mexico moisture has also been present east of the Continental Divide where some of the heaviest rainfall has occurred.
An active subtropical jet stream along with frequent low pressure troughs located across California have aided in this pattern, which is consistent with what we often see during emerging El Nino phases.
Rainfall through the first three weeks of June has been 130-190% of average across Teton County, Wyo. as well as Teton County, Idaho based on reporting weather stations.
The Town of Jackson has received 2.05 inches of rain so far in June, compared to an average of 1.25 inches through the first three weeks of the month. Average rainfall for the month of June as a whole is 1.50 inches, so we are already guaranteed an above-average rainfall month.
Also, this has already been the wettest June in Jackson since 2011 (when 2.12 inches was recorded) and will likely end up being the wettest June since 2010, when an estimated 3.15 inches fell in town (rainfall data was missing at the Jackson station during June 2010, so model-estimated data was used instead).
Rainfall has been even more impressive south and east of Jackson Hole, with month-to-date rainfall ranging from 200% to 450% of average!
The map below indicates above-average rainfall across nearly the entire state. The below-average anomalies showing up around Yellowstone appear to be inaccurate as many of the Yellowstone weather stations do not have complete data this month. The Yellowstone weather stations that do have complete data are reporting above-average rainfall.
Also, notice that rainfall has been above average across a large portion of the West from the Sierra Nevada Range to the Central Rockies, with below-average rainfall across the Pacific Northwest.
Coastal regions of California and Oregon receive little rainfall on average during June, so any departures from average tend to be exaggerated. The same is true for Southern Arizona, where June is the dry season prior to the arrival of the North American Monsoon in mid to late summer.
Here is a list of rainfall totals from June 1-21 compared to average across Western and Central Wyoming along with Teton County, Idaho.
| Location | June 2023 Rainfall (So Far) | Average Rainfall thru June 21st | Percent of Average |
| Dubois | 4.76″ | 1.07″ | 445% |
| Buffalo | 4.72″ | 1.62″ | 291% |
| Casper | 4.36″ | 1.07″ | 407% |
| Riverton | 3.61″ | 0.84″ | 430% |
| Afton | 3.11″ | 1.34″ | 232% |
| Darwin Ranch | 3.09″ | 1.29″ | 240% |
| Worland | 3.04″ | 0.89″ | 342% |
| Lander | 3.03″ | 0.90″ | 337% |
| Cody | 2.61″ | 1.24″ | 210% |
| Alta | 2.58″ | 1.76″ | 147% |
| Moran / Jackson Lake | 2.56″ | 1.37″ | 187% |
| Tetonia | 2.50″ | 1.37″ | 182% |
| Swan Valley | 2.48″ | 1.66″ | 149% |
| Yellowstone Lake | 2.37″ | 1.78″ | 133% |
| Lamar Valley | 2.12″ | 1.80″ | 118% |
| Jackson | 2.05″ | 1.25″ | 164% |
| Tower Falls | 2.04″ | 1.48″ | 138% |
| Moose | 1.85″ | 1.36″ | 136% |
| Rock Springs | 1.59″ | 0.57″ | 279% |
June Temperatures So Far:
Temperatures this month have not deviated significantly from average statewide. Generally speaking, temperatures are running slightly warmer than average across Western and Northern Wyoming, and temperatures are running slightly cooler than average across Central and Southern Wyoming.
Teton County and the Town of Jackson are included in areas that are running slightly warmer than average so far this month. But wait… how can temperatures be running above average when we’ve had so many cloudy and cool days over the past few weeks?
The answer has to do with low temperatures…
Afternoon temperatures are, in fact, running cooler than average. In the town of Jackson, high temperatures are 4.3ºF below average so far this month.
However, abundant moisture and cloud cover have resulted in much milder overnight temperatures than usual. So far, low temperatures have been 6.0ºF warmer than average during the month of June.
Taking into account high and low temperatures, we are running 0.9ºF warmer than average so far this month – in other words, slightly above average, but not by much.
We did experience a cool snap early this week with well-below-average temperatures along with light snow accumulations in the mountains. Snow dusted grassy surfaces down to 8,000 feet on Tuesday morning with the snow stake at Grand Targhee indicating 2-3 inches of accumulation.
Even though we’re at a time of year in which average temperatures are rapidly increasing, this past Monday was the coldest day we’ve experienced in Teton County in several weeks. The high in Jackson on Monday was 55ºF, which was the coolest high temperature reading since May 7th!
Upcoming Weather Pattern
The next week will feature more sunshine and less rainfall overall than we’ve seen in quite some time. But it won’t be completely dry either, and temperatures are expected to be near to slightly below average most days.
On Wednesday, sunny skies and dry conditions can be expected with highs in the mid 60s. This is still about 10 degrees below average, as average highs at this time of year are in the mid 70s.
A widespread freeze can also be expected for the Jackson Hole Valley and Teton Valley under clear skies with a drier airmass on Wednesday night. Lows are forecasted to drop into the upper 20s. While freezing temperatures are not at all unusual at this time of year, we have not seen a widespread valley freeze since May 20.
On Thursday, a more significant warm-up will occur with highs reaching the mid 70s. The weather pattern will then turn more active again late this week as a low pressure system approaches from the southwest.
We will see a slight chance of thunderstorms on Thursday afternoon, followed by a somewhat higher chance of showers and thunderstorms during the evening and overnight hours on Thursday night.
More widespread showers and thunderstorms can then be expected from Friday morning through Friday evening, with Friday afternoon featuring the highest odds of rainfall and lightning activity. Locally heavy rainfall will be possible, and temperatures will also be cooler with highs in the low 60s.
On Saturday, lingering moisture will result in a chance of showers and thunderstorms, though coverage and rainfall amounts will be lower compared to Friday. Temperatures will remain on the cooler side as well with highs in the 60s.
From Sunday through the first few days of next week, we will head into a warmer and drier pattern with highs in the 70s along with abundant sunshine. We may see our next chance of showers/thunderstorms arrive around the middle of next week, but confidence is low.
Looking further out, we should see a gradual warming trend over the final few days of June and into early July. The best moisture and associated shower/storm chances are expected to be just to our north across Montana with the Tetons/Yellowstone right on the southern fringe.
In this pattern, occasional showers/thunderstorms should still be expected heading into early July, but rainfall is expected to be lighter and less frequent compared to recent weeks and temperatures are also expected to be warmer.
In other words, it should start to feel more and more like summer as the calendar flips to July.
Alan Smith, Meteorologist
