Final answer:
The claim that the only month with an average temperature above freezing coincides with the summer solstice is false. Both the Northern and Southern Hemispheres experience their hottest months after the June and December solstices, respectively, due to the time it takes for Earth's surfaces to heat up.
Step-by-step explanation:
The statement that the only month with an average temperature above freezing corresponds to the summer solstice is false. In the Northern Hemisphere, although the summer solstice (around June 20 or 21) is the day with the longest daylight hours, the hottest months are typically July and August. This delay in peak temperature occurs because Earth's land and water masses take time to heat up, a concept comparable to how a pond doesn't warm up the instant the Sun rises but rather late in the afternoon when it has absorbed more heat.
In the Southern Hemisphere, the situation is reversed, with December marking the beginning of summer when the Sun is directly above the Tropic of Capricorn. Similarly, the warmest months are usually after the December solstice. Hence, both hemispheres experience the warmest days of the year later than the respective summer solstice due to seasonal lag.