While it hurts, it is only fair to report all tanks, good or bad, due to weather, or the fact you were moving your brother's apartment and were fully loaded.

ANY car, hybrid or not will have lower MPG in winter and when fully loaded.

For the record, it was -15'F ( 15 below Zero in N.Colorado... not far from S.D. ! ) this time last week, and for 3 days I was in 28 MPG territory.

Colorado is fickle. Today was 73'F and I'm getting 42 MPG.
Since I'm on the same tank, my numbers should be very "average".
-John