Yesterday I spent an hour driving my 2002 Prius south on HW 101 during a typical November storm in the PNW. The winds coming off the ocean and bays was between 40 and 60 MPH. The winds were blowing to the north east. Headwinds are the worst! As I started out the MPG was 42. By the time I reached my destination the MPG had dropped to 37.5. It was the worst MPG for a half tank of fuel I've ever seen on this car. Am I complaining? Not on your life.... it's still better MPG than any other car I've ever owned. Do I wish the MPG was higher? Yes, but then I chose to drive during the storm. I can't complain.
For a Prius, crosswinds can actually be worse than direct headwinds. That is probably what you experienced. Be glad you didn't have a bike rack on the car too. On a major road trip last month with bikes, strong cross winds, and fresh not-broken-in tires, I had some half-tank segments of just 32 mpg.
Bob, if the wind is 100mph, I'll stay home... otherwise I'll be crushed by a tree of a flying salmon.
Sadly, three drivers here were killed by falling trees in yesterday's windstorm. And a transit driver was hospitalized after a tree fell on the front of her bus, but the injury was not life threatening. I haven't yet heard of any motorists being injured by flying salmon. But this is about the right time to get the pictures of the annual salmon-swimming-across-the-highway event as the usual areas flood.