Abrupt Heat Wave/Cold Spell endings

[cheetah2003]

Not really sure if this qualifies as a 'bug', so putting it here.

Seems that when a heat wave/cold spell comes on, the temperature gradually worsens (gets really hot/cold), but when these two events end, the temperature suddenly changes to a more appropriate level for the current season.  Shouldn't it gradually return to 'normal' rather than change abruptly?