John Metcalfe was CityLab’s Bay Area bureau chief, covering climate change and the science of cities.
Forget a White Christmas. Will you get a White Halloween?
Brian Brettschneider, a climatologist in Anchorage, has the answer: very slim. “Halloween is the least snowy winter holiday,” he says. In fact, of all the major U.S. weather stations with a decent amount of records, he says only two (outside Alaska) have at least a 50 percent likelihood of experiencing a “White Halloween”: Mount Washington, New Hampshire, and Stampede Pass, Washington. (Both are places not known for human habitation, let alone trick-or-treating.)
To hammer in how infrequently snow and our annual horrorfest mix, Brettschneider’s made a map of snow probabilities for October 31 using data from “first order” weather stations. (He chose stations that hold at least 20 years of Halloween records, although some have many more years, in some cases stretching back to the early 1900s.) The map shows that for near-ironclad odds of catching flakes in your candy sack, you pretty much need to head to Canada or Alaska:
Brettschneider, an inveterate weather mapper who also’s made a guide to the ultimate 70-degree road trip, shares these historical nuggets:
The most southerly “White Halloween” goes to Midland, Texas, when 0.1" of snow fell on October 31, 1991. Not to be outdone, parts of the Texas Panhandle had 6" of snow on that same date. Valdez, Alaska, holds the record for the most snow on Halloween (24.6" in 1999) and the Summit, Alaska, weather-service office has the record for greatest Halloween snow depth (29" in 1905).
For folks who are wondering what was up with that early-1990s Texas snow, a “perfect storm” in the Atlantic was affecting weather in the South by driving moisture up from the Gulf. Soon snow and ice were falling throughout the region, making for a strong blizzard that killed nearly two-dozen people.
Here are a few city-specific records for snow on Halloween. It’s always white in beautiful Barrow, Alaska:
- New York, Central Park: 0 of 103 years. Despite a freakish and damaging late-October snow in 2011, it all appears to have melted by Halloween.
- Boston, Logan Airport: 0 of 66 years
- Chicago, O'Hare: 1 of 56 years
- Denver, Stapleton Airport (now closed): 13 of 67 years
- Amarillo,Texas: 2 out of 67 years
- Fairbanks International Airport: 82 out of 85 Years
- Anchorage International Airport: 33 out of 65 years
- Barrow, Alaska: 91 out of 91 years
What about Hawaii, whose volcanic peaks get their fair share of snow and freezing fog? The situation is pretty much the same as with the Lower 48. “They are far more likely to see snow in February through April than in October,” says Brettschneider, “so while the summit records are rather incomplete, they are nearly certain to be in the Under 5% [probability] category.”