cold
At 30.6° Fahrenheit (-0.8°C), February 2021's mean continental U.S. temperature was 3.2° F (9.5%) below the month's 20th Century average, ranking this the 19th coldest February since 1894 (127 years).

Of course, this very severe drop accords with our mid-1990s 140-year post-Little Ice Age "amplitude compression" thesis, positing serial 50-40-30-20 year warm-cold spells from AD 1890 to 2029. At that point, intra-decadal oscillations, whipsaw global temperatures, will confirm the onset of a cyclical 102-kiloyear Pleistocene Ice Age dating from AD 1350, ending the 12,550-year Holocene Interglacial Epoch.

Though abrupt chill-phases such as the 1,200-year-long Younger Dryas (12,950 - 11,750 YBP) or Mesopotamia's devastating Dark Millennium (3,800 - 2,800 YBP) can occur in months, these are not climate-shifts but episodic phenomena due to cometary/meteoritic impacts or oceanic current fluctuations.

As Ice Age Now has long noted, a periodic 12,000-year geomagnetic pole reversal conjoined with Svensmark-Zharkova's increasing global cloud-cover due to a looming 8-cycle Super-Grand Solar Minimum through AD 2108 per diminished solar magnetic fields (SMFs) may induce abrupt glaciations when winter snows fail to melt in summer.

Over 3.6 million years from the mid-Pliocene, this regularly recurring plate tectonic-driven sequence is due to last another 15 to 25+ million years, affecting Quaternary Periods succeeding the short-lived Pliocene and Pleistocene.