Fig. 1.

Early and late winter precipitation at the Irvine Ranch Water District (<3 km from the study sites) from the National Climate Data Center. We calculated cumulative precipitation during the growing season (100 days after the first 72-h period with rainfall ≥1 cm). Mean cumulative precipitation for days 1–50 and days 51–100 for each of the five growing seasons leading up to 1997 and 2004 were calculated, and values are plotted as deviation from this mean. Shaded bars indicate cumulative precipitation during the first 50 days after rainfall. Black bars show cumulative precipitation in the subsequent 50 days.