Most of California experienced the severest dry spell on record in 1976-77; 1978 was one of its wettest rainy seasons. The economic and environmental impacts of the drought were significant. Comparisons of nonoverlapping, twenty-year periods between 1921 and 1977 produced few statistically significant differences in either means or variances. The probability of occurrence of extreme seasonal precipitation increased in the northern two-thirds of the state in the period 1961-77 relative to the period 1921-60, but decreased in the south. The chance of getting a total seasonal precipitation less than forty-three percent of the mean in any one year in the Sacramento Valley and the North and Central Coast regions since 1961 has increased to 1 in 15 from 1 in 20 in the period 1921-40 and 1 in 21 or 25 over the whole period of record. The period 1961-77 is statistically more similar to 1860-80 than to either 1921-40 or 1941-60. No relationships could be established between hemispheric warming and cooling and precipitation variability in California. © 1979, Taylor & Francis Group, LLC. All rights reserved.
