BETHLEHEM, Pa. — The weather can change rapidly this time of year, meteorologists warn, with daily temperatures ranging from unseasonably warm to unseasonably cool.
Because of that roller coaster, it’s the time of year when farmers will carefully monitor temperatures that can affect the birds, the bees, the flowers and the food supply.
- We're nearing the time of year when the Lehigh Valley typically sees the last frost and freeze dates, but temperatures are up and down, putting bees and plants at risk
- With inadequate pollination to the trees, our orchards could see reduced production this season
- According to the Penn State Extension, it’s just about time to safely plant things such as peas, cabbage, lettuce and carrots
Temperatures at or below freezing are bad news for bees, especially, and honey bees alone pollinate 80% of all flowering plants, including more than 130 types of fruits or vegetables, according to the U.S. Department of Agriculture.
It means that roughly one of every three bites of our food is created with the help of pollinators.
But bees only fly when air temperatures are above 55 to 60 degrees. Being in dropping temperatures causes exposure – and potentially death.
READ: Frost as foe: Scholl Orchards brings something new to the fight against crop-killing cold
With inadequate pollination to the trees, our orchards could see reduced production this season. The same trees — apples, peaches, plums and more — also could be harmed by temperatures as low as the upper 20s and lower 30s.
And just like farmers, folks anxious to begin their spring gardening also are looking toward the last frost and freeze dates.
Last frost and freeze dates for our area
According to the National Weather Service, the average last freeze date for Allentown is April 25, and the average last frost date is May 5.
Dates differ in other climate sites across the Mid-Atlantic, with an urban heat island and moderating effects of the ocean resulting in a much earlier date for Philadelphia and the Atlantic City Marina compared with other locations.
Map of the avg last freeze date for our CLI sites. The urban heat island and moderating effects of the ocean result in a much earlier date for Philly and the AC Marina compared to others. The Pine Barrens also influence AC Airport into being one of the later locations. pic.twitter.com/UhszxS3U40
— NWS Mount Holly (@NWS_MountHolly) April 4, 2023
The weather service also doesn’t keep records of frost, but says frost is associated with a sensor level temperature of 36 degrees or less, so it’s the value forecasters use to indicate when frost is likely.
As requested, average last "frost" date. Same caveats from the last map apply. Note: we don't keep records of frost, but typically frost is associated with sensor level temps of 36 or less, so we use that value to indicate when frost is likely. Often, there isn't frost at 36. pic.twitter.com/rmSNylvI9e
— NWS Mount Holly (@NWS_MountHolly) April 4, 2023
A planting guide for early spring
According to the Penn State Extension, it’s just about time to safely plant things such as peas, cabbage, lettuce and carrots.
But you’ll have to be patient if you’re looking to plant tomatoes, peppers and cucumbers. Those are the plants that shouldn’t go into the ground until at least the middle of May.
According to the weather service, the latest frost on record in Allentown took place May 30, 1949. The latest freeze on record took place May 21, 2002.
