History of first snow of the season for thousands of U.S. stations

November 16, 2017


By the calendar, winter is still a month away. For many of us, though, winter starts with the first snow of the season. By that definition, this map shows the earliest first day of winter recorded at thousands of U.S. stations during their period of operation. Zoom in and click on a dot to find out the earliest date snow has fallen in your neighborhood based on these station histories.

About the data

As we've published about before in the Beyond the Data blog, snow observations are among the most hit and miss in terms of the completeness of daily histories. These locations are a subset of the complete Global Historical Climatology Network that met various quality controls for reasonableness and completeness of snow cover.  Most stations have at least 20 years of data. A few have a shorter history, but are otherwise of good quality (e.g., little to no missing data).

This map should not be interpreted as the “earliest ever” first snow of the season at a given place. It is simply the earliest date of first snow at a given station during its period of operation. As you can see if you explore the map, the length of station histories varies, and to describe the complete history of snowfall at a given place, climate scientists might have to carefully piece together time series from stations at or near the same place that have operated through different periods of history.

Data provided by Jared Rennie.