Updated: May 4, 2021
A lot of people are worried about frost tonight. As you should be. These things happen and it's good to be prepared. I personally find it's better to either not care at all or to go the extra mile to sleep comfortably. This can be a stressful time for farmers and hobbyists. Like I said.. take either path and you'll be fine with the results tomorrow morning regardless. I learned that the hard way last year.
This year on 4/22/21 there is a freeze watch issued for my location. Even though the forecast is predicting a low of 37, frost is still possible. Especially if there's clear skies and it's a still night. 37 makes me feel good about the situation, but that's a prediction and I could very easily see temperatures 5 degrees or more colder than what's predicted. Keep in mind... when it comes to figs the duration & severity of the frost is quite important. Also how far along are your trees? Do they have fruits? Maybe 1-3 leaves? A light kiss of frost that lasts only 1-2 hours isn't going to do much to trees that only have swelling buds. If it's something more severe, you may lose some buds and what's more likely, some leaves and fruits the further the tree is progressed. I've also seen frosts so light that it merely only minimally damages
the leaves/fruit cosmetically.
Believe it or not.. my trees have already seen a light frost this spring when we hit a low of 26. I took the route of doing nothing. Oddly enough.. it wasn't until a week later that I realized we even potentially had a light frost. Going around the yard and inspecting some trees, I realized that I lost some buds and breba on a few in ground trees that are in frost sensitive areas. While my many other rooted cuttings on the patio were completely unaffected. Keep in mind.. that was a pretty extreme temperature to be flirting with. Anything below 25-26 is asking for trouble, so not only is the duration/severity of frost important, but so is the temperature.
If I had to guess, most of Southeastern PA and the surrounding areas will see some sort of frost tomorrow morning. The closer you are to water, a major city, if you're surrounded by concrete and if you're on higher ground mean that you're less likely to see frost. Your microclimate is immensely important to consider. I highly suggest checking out this map - Anyone along the edges of the frost line should strongly consider the cost/benefit of protecting your trees. It can be a lot of work and often it was all for nothing. Then again... you'll sleep comfortably. I can't tell you what to do but only share the information to make your decision easier.
Taken from the Farmer's Almanac: Frost Advisory: Issued when minimum temperatures are expected to be between 33° and 36°F (0.5° and 2°C). Skies are generally clear and winds light. Freeze Watch: Issued when minimum temperatures are expected to be 32°F (0°C) or less within the next 24 to 36 hours. Freeze Warning: Issued when minimum temperatures are imminently expected to be 32°F (0°C) or less. Hard Freeze Warning: Issued when minimum temperatures are expected to be 28°F (-2°C) or less.
I would absolutely take measures to protect my trees in a freeze watch, warning and a hard freeze warning. Only in the advisory can you get away with taking the doing nothing route.
What I'm doing:
As I said, the forecast is predicting a low of 37. If that holds true, I have nothing to worry about. However, to sleep soundly I'll be going around the yard late tonight (when the wind dies down) to protect 2-3 annual plants, figs that have already been hit by a frost, trees in frost sensitive areas and trees that are too young to recover from a frost. Moving or covering are your only options. Get creative. Tarps cover a wide area. Lie things down close to a warm structure and cover. Heavy duty trash bags also are a great option. Cover the top of the plant with the trash bag and tie it around the trunk. I also have used nursery pots. Just put it right over the tree. Weigh it down.