I live in Seattle, a city known for good coffee, great views and lousy weather (a friend once told me you don't tan in Seattle—you rust). As a matter of fact, rain is coming down as I write this, which means yet another day that my two young children will need to find fun indoors, unless we suit up to splash in puddles.

So a new study linking high rainfall with higher rates of autism caught my attention. Like many parents, I worry about autism. What's especially anxiety-provoking about this condition is that so little is known about what causes it and what (if anything) parents can do to protect their children. Some experts now think the condition is triggered by a combination of genetic and environmental factors, but while the evidence for genetic factors is strong, the role of possible environmental influences remains very uncertain.

In the study, researchers charted rates of autism and rainfall for counties in Washington, Oregon, and California. They found that counties with more rainfall had higher rates of autism. In my home state of Washington, for example, the counties west of the Cascade Mountains had four times the rain and twice the rate of autism as counties to the east. Of course, the theory that more rainfall could trigger higher rates of autism seems improbable. One possibility the researchers suggest is that children cooped up inside because of rain may have greater exposure to possible triggers, such as chemicals in household cleaners, or television, or not enough exposure to vitamin D-generating sunshine. But these are just untested theories at this point. The researchers caution that far more research needs to be done.