Every year, as the air warms, the leaves turn, or the first snowflake falls, we casually refer to the "start of a new season." But if you ask five different people when winter officially begins, you might get five different answers. Does winter start with the winter solstice (around December 21), or on December 1? Is the first day of summer June 1 or June 20?
Meteorologists and climatologists use fixed calendar dates for simpler record-keeping and forecasting. These seasons align more closely with the annual temperature cycle. The dates are fixed and do not vary by year. when do the four seasons start and end
(Exact hour/minute changes every year; consult an astronomical almanac for precise timestamps.) Every year, as the air warms, the leaves