Spring is more or less already here, based on measurements of first leaf growth around the region. But hard freezes threaten vulnerable plants this weekend.
Data collected by the National Phenology Network shows that buds are swelling and leaves sprouting across the southeastern quadrant of the country. Hundreds of individual reports of plant growth show spring's arrival in detail, with first leaves appearing around the Baltimore region around Feb. 24-26.
Such reports are 21-24 days early, according to the network's historical data.
The earliest spring growth always faces a risk of freeze or frost damage, but that is an even bigger concern this year because spring has arrived so early.
Temperatures are expected to drop to freezing early Friday morning (with a 40-50 percent chance of snow showers) and then well into the 20s Saturday and Sunday mornings. Both weekend mornings are expected to reach the mid-20s.
Lows also reached the 20s last weekend, but each afternoon of warmth is coaxing new plant growth. High temperatures reached 65 degrees on Tuesday, the last day of meteorological winter, and 75 degrees Wednesday, the first day of meteorological spring.
Officially, spring doesn't begin until the vernal equinox, at 6:28 a.m. March 20.