Oh the difference is likely at least that much on most clear calm nights.
At my house I can be up to 10 degrees lower than the base of the ski area at 1,500ft sometimes where it's almost always mixed at least a little with mid-slope climo. The inversion level is often right around 1,000-1,200ft. I'll leave in the morning and it could be 32F only to find it's 40F up there with a breeze. Then it'll be 60F there in the afternoon and 65F at my place.
You can actually see it in the MVL/MPV normals around here... MVL is 700ft and MPV is almost 1,200ft but because the overnights on clear nights can be colder, the daily mean temperatures are pretty even. One site gets a degree or two lower for the mins and the other gets a degree or two lower on the maxes.
Alex is still at just over 1,500ft so even his daytime temps stay pretty cool... he really found a cold spot there. Pretty crazy little microclimate.