Spearfish enjoys a moderate climate with dry, sunny weather most of the time. 50 degree temperatures are not uncommon during winter months. Summer days are seasonably warm, but when the sun sets evenings are refreshingly cool. Summer is followed by a long, pleasant autumn season.
- Spearfish Creek is the only creek known to freeze from the bottom up. Spearfish Creek also flows from the South to the North!
- Spearfish is listed in the Guinness Book of World Records because an unusual event happened in 1943. Spearfish is recorded as having undergone the greatest temperature variance. On January 22, the temperature shot from –4°F to +49°F in less than two minutes, then dropped from +55°F to –5°F. Fifteen minutes later the mercury rose to +55°F.