JACKSON, Wyo. – May 2024 is on track to be the coolest and snowiest May in Jackson Hole since 2011. Over the next week, seasonal temperatures and occasional showers can be expected, while longer-range models are hinting at above-average temperatures in June.
Preliminary May Recap
May is traditionally an unsettled weather month in Jackson Hole, but this May in particular has been colder than normal as spring has taken its time to really get going. We did see a nice stretch of warm and sunny weather earlier this week, however, with a high of 77ºF on Tuesday.
For the month of May (through May 29), the town of Jackson has had an average high of 57.0ºF and an average low of 32.0ºF. When averaging these two values together, temperatures have been 3.2ºF below normal this month. With only two days left in the month, this is likely to end up as the coldest May in Jackson since 2011.
Precipitation is going to end up right around average for the month in the town of Jackson. As of Wednesday morning, Jackson has received 2.06 inches of precipitation this month and we have seen light rain showers since the last report during the day on Wednesday. Average precipitation for the month of May is 2.08 inches, so we are right there.
For the water year (since October 1), Jackson has received 13.88 inches of precipitation, compared to a season-to-date average of 12.89 inches (based on 15-year averages).
We saw several impressive late-season snow events in the Tetons this month. The Rendezvous Bowl Plot at 9,580 feet has received 55 inches of snow this month, which is the most snow during the month of May at this location since 2011 when 58 inches fell. Average May snowfall at this location is 30 inches.
The town of Jackson has also received 7.6 inches of snow this month, which accumulated during the first week of the month. Although there are years with missing data, this is officially the snowiest May in town since 1973. Average May snowfall in town is only 0.7 inches.
For the 2023-2024 season as a whole, the town of Jackson will finish with 112.4 inches of snowfall which is above the 15-year average of 93 inches. Oddly enough, Jackson also received 112.4 inches of snowfall exactly in 2022-2023, though mountain snowfall was heavier last season compared to this season.
Current and Upcoming Weather Pattern
A low-pressure system moving across the Northern Rockies on Wednesday has produced off-and-on showers across Teton County, with some occasional lightning activity also noted.
A cold front also moved through with a high of 61º occurring late in the morning in Jackson, with temperatures having since fallen into the 50s during the afternoon. The average high for the date is 66ºF so we have fallen below average again for the time being.
Cooler temperatures and breezy conditions will prevail behind the front on Thursday with lows in the low 30s and highs in the upper 50s. A warming trend will then take hold late this week as high pressure rebuilds over the region with highs in the 60s on Friday and 70s on Saturday.
The pattern will turn more unsettled from Sunday to Tuesday as a couple of low pressure systems are projected to pass just north of our area, resulting in low to moderate potential for showers and thunderstorms.
Any rainfall is expected to be light at this time, but we’re far enough out that this could always change if the systems were to trend further south. Highs are projected to range from the upper 60s to low 70s during this period.
June Outlook
June tends to be a very nice month in the Jackson Hole region as we transition from a spring pattern into an early summer pattern. During the month of May, Jackson has an average high and low of 61ºF and 33ºF. During June, these averages rise to 72ºF and 40ºF respectively (15-year averages).
We can still see stretches of cool and unsettled weather in June, however. The Tetons around 9,000-10,000 feet usually see at least one more accumulating snow event in June and the average last freeze of the season in the town of Jackson is on June 19.
The town of Jackson averages 1.59 inches of rainfall in June, though annual variation is significant. In the past 15 years, the wettest June was in 2009 when 3.80 inches of rain fell, while the driest June was in 2012 when only 0.19 inches of rain fell.
Thunderstorms become more common in June with an average of 8 thunderstorm days in Jackson (based on data from the National Lightning Data Network and Storm Prediction Center).
Severe thunderstorms are less common in Jackson Hole compared to many parts of the U.S., but they do happen on occasion at this time of year with damaging straight-line winds (60+ mph gusts) typically posing the greatest risk with storms.
Less frequently, we can see severe hail with thunderstorms in Teton County, which is defined as hail of one inch or more in diameter. During June of 2022, a supercell thunderstorm tracked across Teton County, producing damaging hail in Teton Village before a rare EF-2 tornado touched down in the Gros Ventre Wilderness east of Jackson.
Severe thunderstorms and tornadoes are more common in Eastern Wyoming, and the state as a whole averages 12 tornadoes annually. June is typically the most active month of the year for severe weather in Eastern Wyoming.
For June 2024, medium-range models are projecting a strong ridge of high pressure to build over the Western U.S. during the first week of the month, with above-average temperatures and drier conditions expected in Jackson Hole beyond next Wednesday, June 5.
Longer-range models are projecting the month as a whole to be warmer than average, though confidence decreases beyond mid-June as weather model skill decreases significantly beyond two weeks. Also, there are no clear signals yet toward above or below-average precipitation for the month of June as a whole.
Alan Smith, Meteorologist
