A number of methods have been proposed for measuring the added risk of a road accident during rainy weather. These methods are reviewed here, and two of them are applied, with adjustments, to data from Israel and the United States. Their accuracy, however, is limited because surrogates have to be used for traffic exposure to rain. Nevertheless, results to indicate that the added risk of an injury accident in rainy conditions can be substantial: two to three times greater than in dry weather. And when a rain follows a dry spell the hazard could be even greater.