Changes in daily motor vehicle accidents during 1990 are examined for the City and County of Honolulu. Adjusting for changed reporting criteria, daily accidents fluctuate according to an interaction between traffic volume, weekday travel patterns, holidays and weather. Fridays, particularly, and Saturdays have more daily accidents. Minor holidays generate more daily accidents, but major holidays generate fewer daily accidents, primarily because of lower traffic volume. Rainfall increases the risk of accidents substantially. The interaction between afternoons and rainfall is particularly dangerous. Unemployment also appears to reduce daily accidents.