Dowbrigade

RAINY weather influences road deaths in a far more complicated
way than previously thought. Rain does not increase the number of deaths
in crashes, provided it rained the previous day. But a heavy shower after
a dry spell causes a lethal surge in accidents.

Daniel Eisenberg of the University of California,
Berkeley, stumbled across the link while studying the dangers of driving
under the influence of drugs. He knew that there are more accidents on
rainy days and wanted to show that this factor wasn’t influencing his results.

But when Eisenberg calculated the annual and monthly figures for rainfall
taken from the US Weather Service’s 20,000 weather stations, and compared
it with nearly 430,000fatal crashes between 1975 and 2000, he found that
the number of deaths fell in rainy months..
Eisenberg says the longer the dry period before it rains, the higher the
number of deaths.

from Newscientist.com via Eureka Alert