Lower mileage in the East Coast winter. Why?

Temperature vary between 30 degree Celsius in summer to -10 degrees in winter in northeast USA. I bought my CRV 3 years back and observed that every winter the car returns a lower mpg ( ~4-5 mpg or 20% less compared to summer). This is the 4th winter and same story again. The impact on mpg is more during the first 4-5 miles in a cold start, but the overall mpg returned is less even once the engine reaches the operating temperatures. My observations - It could be engine not producing enough power (lean burning) or higher rolling resistance. I could feel vehicle speed dropping fast as I step out of the accelerator or higher push in accelerator to maintain a given speed in winter compared to summer in the same daily commute routes. The car feels more rigid in winter. Would like to understand why this happens, and what can be done to reduce the drop in mpg.

URL: