The weather described in the novel The Road was bleak - clouds, rain, ashfall, some snow. The clouds were almost a separate character in the novel!
The weather in Western Pennsylvania in winter matched that, except for the ashfall. Our region is one of the cloudiest places in the country, especially in the winter.
In the early '00s, we didn't have all that much snow over the winter months. We tended to have more cold rain. The last couple of years, we've had light snow for most of Janaury and February. Our immediate region doesn't tend to get that much snow all at once. We had a couple of substantial snowfalls in 1993 and 1994, but, since then, we had maybe one 9" snowfall. We're south of the Great Lakes snowbelt, and a little too far west to get frequent snowfalls from Atlantic winter storms. But, Western Pennsylvania can have snow flurries any time from October through April.
Mid June 2008 Postscript: During the first part of filming in Western PA (late-February-early April), the weather was mostly cloudy, cool, rainy. And then the sun came out. We had beautiful May weather during most of April. About the time the weather turned really nice in the Pittsburgh area, they were shooting interiors in a warehouse in town (reportedly, the bunker scenes). The next week, at Conneaut Lake Park and on Lake Erie, the weather was cool and breezy, but still nicer than usual. The cast and crew left for Oregon in early May. And then, the weather turned crappy (it was pretty awful in eastern Oregon, too). We had cool, rainy April weather for most of May. In late May, summer hit Western Pennsylvania. The weather since about May 20 has been sunny, and since it was so damp over the winter, Western Pennsylvania has gone from being a post-apocalyptic wasteland to being almost tropically green. I won't make the joke about maybe global warming is a good thing for us, because it isn't a good thing for most of the rest of the world.
Since so much of the action of the book took place outdoors, I tracked local weather conditions from late February through late April 2008. Later, the curious can compare the recorded weather against scenes from the movie, to try to figure out when the location footage was shot.
The conditions described were for the Pittsburgh area. When they shot location footage in the Alleghenies, there was generally more snow on the ground, it was usually a little colder and often it was windier.