I needed to verify a weather pattern for a back story in a future Jess Barker book. Of course my first thought when I think of weather is Farmer's Almanac not the Weather Channel. I've got farmer genes in my blood, I think of the Almanac as my default reference book for pretty much anything and buy a new one every year.
To my delight I found on a very cool research tool on their website: a historical weather calendar. It even includes snow depths for states with snowfall. Pretty cool!
Just thought I'd pass this on for anyone that may be doing historical story lines that needs to verify weather data.