ROCHESTER, N.Y. (WROC) — As we dive deeper into the month of May, you may be wondering how much longer you may need to protect your plants and flowers from potential frosts and freezes. This past May has been a chilly one, and we’re now turning the page into warmer temperatures that are much more “spring-like” than what we’ve been seeing. With warmer temperatures in mind, does this mean we’re done seeing frost?
When is the average last spring frost date?
The average date of the last light freeze in spring, or the first light freeze in fall is known as the frost date. The classification of how severe a freeze is, is dependent on temperatures and how sensitive the plants at stake are.
Remember: a freeze occurs with temperatures around 32° or lower, but frost can develop at temperatures slightly above freezing.
- Light freeze: 29° to 32°F (tender plants are killed)
- Moderate freeze: 25° to 28°F (widely destructive to most vegetation)
- Severe freeze: 24°F and colder (heavy damage to most garden plants)
Temperatures are typically forecasted around eye level, or 2+ meters above the surface. Even if temperatures aren’t quite at freezing above the surface, that doesn’t mean that temperatures at the ground are the same. Frost can still develop at the ground where colder, more dense air is able to sink to the lowest possible point, which means that when temperatures are forecasted to be slightly above freezing even in the mid to upper 30s, the ground could still be cold enough for frost.
According to the National Climatic Data Center (NCDC) about half of the northeast has already past the date of the average last frost. Some areas of New York State still have a little ways to go before climatologically speaking, is the last time we can see frost.
Most of the Western New York region’s average last freeze runs from May 1st-15th while parts of the Southern Tier and hills of WNY have through May 31st. This means there are parts of the region that still could see frost according to the data of when the average last frost/freeze is. This doesn’t necessarily guarantee whether or not the weather will cooperate, so this is used as a general guide.
According to the Farmer’s Almanac, the average last spring frost for the city of Rochester is on or around May 3rd, which means we’re well past the potential to see frost at this point in time. It’s important to note that these dates are not exact, and come from a series of climate data based on previous occurrences. It’s still possible to get frost even after the average last date depending on the local weather patterns at stake, but now that temperatures are starting to warm the chances are becoming more slim.
The trend is our friend if you’re looking for warmth and less potential for frost with above average temperatures likely toward the second half of the month.
The average high and low temperatures for Rochester as of this writing are 69°/47°, and we’re beginning to make that transition from chilly mornings and mild afternoons to more tolerable temperatures all around heading into next week.
Understanding frost and freeze normals are helpful for both agriculture and gardening. This can guide when the right time for farmers is to start planting is, and whether or not they need to wait. There still is that risk to plants if a frost or freeze were to occur any time temperatures drop into the mid 30s even outside of the expected climate normals. Although, when we have a better idea on when we typically see our last spring freeze, we can get a better grasp on when the best time is to start planting crops for the season.
You can get the local forecast HERE.
Even though frost can occur with forecast temperatures above freezing to an extent outside of frost “season”, we still use climate normals as a helpful guide when an area could see its last potential frost. At the moment, the odds are becoming increasingly low at seeing any more frost especially in and around Rochester.
~Meteorologist Christine Gregory