Researchers at the North Carolina Institute for Climate Studies have discovered that a light drizzle can increase the risk of a fatal auto accident by 27 percent. They reached their conclusion after analyzing 125,012 fatal car crashes that occurred between 2006 and 2011 in Connecticut and the rest of the 48 lower states. They also factored in how many cars were on the road.

More importantly, researchers were able to use weather radar data to calculate rain and snow conditions, whereas previous studies had to rely on the less precise information given in police reports and by the nearest weather stations. This data showed how hard it was raining or snowing at the time of each crash.

Less than one-tenth of an inch per hour of rain can still increase the risk of a fatal car crash. That risk goes up 75 percent in moderate rain and two-and-a-half times in heavy rain. The Northern Rockies and Upper Midwest are the most dangerous regions for rain- and snow-related crashes; the Northeast and Southeast are the safest (researchers believe this is because the east is more urban and drivers go more slowly as a result).The results corroborate those of past studies. For example, the Bulletin of the American Meteorological Society once found that rain, snow and ice make a deadly car crash 34 percent more likely.

Drivers who fail to take the weather into account and cause an accident could be deemed negligent. Occupants of other vehicles who have been injured in such a crash might want to have legal assistance when seeking compensation for their losses.