Arcata has a climate that confuses people. It doesn’t snow, it rarely gets hot, and January looks about the same as July on a thermometer. The precipitation is a different story. Nearly all of it falls between October and April, and the summers are dry enough to make you forget it rains at all.

I came across John Johnson’s Milwaukee weather visualizations and thought the same approach would work well for Arcata, especially the cumulative precipitation chart. Milwaukee gets rain year-round. Arcata gets a firehose in winter and nothing in summer. That contrast should look dramatic on a cumulative curve.

Data comes from NOAA’s GHCN-Daily network, Arcata/Eureka Airport station (USW00024283), with records back to 1992.

Cumulative precipitation

The steep climb from October through March is where most of the ~40 annual inches land. Then flat. The ribbons show how much year-to-year variation there is — wet years clear 50 inches, dry years barely crack 25.

Daily high temperatures

This is the boring chart, in a good way. The marine layer keeps daily highs between 50°F and 65°F for most of the year, with almost no summer spike. Red dots are record highs for the date, blue are record lows.

Code

R scripts are in the site repo. Run retrieve_data.R first, then the two build scripts.