John Metcalfe was CityLab’s Bay Area bureau chief, covering climate change and the science of cities.
Crunching the historic numbers shows Florida and New England like it moist.
What are the odds of seeing your sparkler fizzle in a lousy downpour this July Fourth?
Well, if you live in California or much of the West, it’s as low as zero to 10 percent. Florida and the Gulf Coast, as well as spots in Appalachia and New England, have a more liquidy likelihood of 30 to 40 percent. And the southwestern sides of Maui and the Big Island are practically doomed to a dousing, with chances ranging from 50 percent upward.
That’s according to this NOAA map of historic rain probabilities in the U.S. It shows in moist-looking shades of green/blue each region’s odds of getting 0.1 inches of rain, as calculated from three decades of climate-normals data. Why’d the mapmakers choose 0.1 inches? “Because that’s plenty to drench your crepe paper float, make your hot dog buns soggy, or drown out your fireworks,” they write. Here’s more:
In the [contiguous U.S.], the highest chances for rain on your parade would be in southern Florida (40-50%), followed by the highest elevations of the Appalachian Mountains in North Carolina and West Virginia, and the Northeastern border with Canada, where chances of rain on July 4th have been 30-40 percent. These places reflect locations with, historically, the combination of abundant available moist air and ways to lift that moist air, in the form of mountains or strong daytime heating.
For weather dorks, NOAA’s also made an interactive ESRI version that lets you zoom to cities and towns for exact probabilities (e.g., Devil’s Garden, Florida, sounds quite unhellish with 41.4 percent rain odds). Meanwhile, here are Alaska and Hawaii: