Major North American cities replaced by cities at the same latitude.
Rome owes much of its climate to its location near the Mediterranean Sea, which acts as a massive heat reservoir, keeping winters mild and summers hot and dry. Warm ocean currents, such as the North Atlantic Drift, further help moderate temperatures across the region.
Chicago, by contrast, lies deep inland on the North American continent, far from the ocean. Its continental climate causes rapid heating and cooling of the land, producing hot, humid summers and cold, snowy winters. The city is also influenced by Arctic air masses from the north and can experience extreme weather from the Great Plains.