Temporal and Spatial Distribution of Lightning Strikes in California in Relation to Large-Scale Weather Patterns

The temporal and spatial distribution of lightning strikes varies across California and has a differential effect on lightning fire ignitions. We analyzed 16 years of lightning strike data obtained from the National Lightning Detection Network to determine how the distribution of lightning strikes was affected by geography, topography, and large-scale weather patterns. Although there were significant differences in the number and density of strikes among bioregions, the annual, monthly, and hourly patterns were similar. The number of strikes increased with elevation. Strike polarity varied by month, and mean peak positive current, mean peak negative current, and number of return strokes per strike varied by bioregion. Weather patterns associated with lightning included strengthened high pressure cells stationed over the western United States that deploy moist monsoonlike air masses and promote rising motions, especially over mountain features. Understanding the variation in lightning strike distributions provides insight into the role of fire in different bioregions of the state and aids in the prediction of wildland fire occurrence.