PENNSYLVANIA, USA — The average start to the growing season in the Scranton and Williamsport areas is the last week of April. It, of course, is not an exact science, but since record-keeping began in 1901, the average last 32-degree temperature recorded for the spring season is around April 25 in Scranton and around April 28 in Williamsport.
In colder places, like the Poconos and the Northern Tier, the average start to the growing season is closer to around now, mid-May.
But of course, we could always have a late-season frost or even a hard freeze, killing anything you have already planted.
With temperatures expected to fall below freezing all across northeastern and central Pennsylvania Wednesday night, we decided to take a look back at just how often that has happened this late in the season.
The latest below-freezing temperature ever recorded in the spring season in the Scranton area was in 1956. It fell below 32 degrees on May 25 that year.
Since record-keeping began, this has only happened after May 17 five times; the most recent was in 2009 when it fell below 32 degrees on May 19.
It does not even need to be below freezing for frost to form. If other conditions are right, like a clear sky, light winds, and moisture in the air, patchy frost can form between 38 and 42 degrees. Areas of frost are likely between 37 and 33 degrees, and a widespread frost or freeze can and will happen with temperatures below 32 degrees.
Wednesday night's late-season forecasted freeze comes after this past meteorological winter—December, January, and February—ranked as the warmest ever on record.