Climate Grass Valley has a hot-summer Mediterranean climate (Köppen Csa) with warm to hot, dry summers and wet, cool, rainy winters. Summer is very dry, but thunderstorms may occur. Rainfall averages over per year, in extreme contrast with the semi-arid valley below, which average as low as in some parts. The high rainfall also gives the area green vegetation typical of an oceanic climate. This contributes to a heavy fuel-loading of brush and grass, which dry out during the near-rainless summer, posing a wildfire hazard.
Climate Grass Valley has a hot-summer Mediterranean climate (Köppen Csa) with warm to hot, dry summers and wet, cool, rainy winters. Summer is very dry, but thunderstorms may occur. Rainfall averages over per year in extreme contrast with the semi-arid valley below, which average as low as in some parts. The high rainfall also gives the area green vegetation typical of an oceanic climate. This contributes to a he,avy fuel-loading of brush and grass, which dry out during the near-rainless summer, posing a wildfire hazard.