Therefore; is it safe to plant?
I would definitely hold off planting anything frost/freeze sensitive that will germinate the next week to 10 days. A pronounced cool spell through this upcoming week anyway, will definitely take a bite out if that above normal average temperature accumulated this month. A return upper wind flow, back cross Polar will take hold this week. This pattern is much like the bitter cold, cross Polar flow seen recently in mid to late winter. Of course, the air has moderated some since then and will continue as the solar angle increases with the spring but will still carry a punch. Frost, freezes and possibly even a period or two of snow flurries are all in our near term weather scenario. The outcome will depend on the actual coldness of the air mass over the region and whether or not cloud, cover dissipates overnight allowing for good radiational cooling along with local temperature affects.
As noted in my map above, Earth Day is this Wednesday. It is what it says, a day to reflect on our mother planet and to appreciate our life giving environment. Earth Day began in the early 1970s as we became more and more concerned about our pollution of environment and the longer term affects.
Earth Day Flag
Next up - Record Breaking Late Spring Snowstorms & What's May looking like?
Bill Deedler -SEMI_WeatherHistorian