Frosty mornings will mean trouble for plants in the Midwest and East into this week

Despite recent episodes of warm weather, a few rounds of frosts and freezes are ahead for parts of the eastern half of the country into the last full week of April. AccuWeather meteorologists warn that temperatures can get low enough in this region to threaten vegetation.

The blasts of chilly air will come in two rounds, first early this week, and then again midweek, as cold fronts sweep south from Canada. Temperatures for a few mornings can drop to or even below the freezing mark from the upper Midwest to eastern New England and as far south as North Carolina and Tennessee.

While it may be the last frosts and freezes of the cold season for some ahead of a big warmup to end the month, precautions will need to be taken to protect any sensitive vegetation into this week.

The first mornings where a frost or freeze can occur will come to start this week, warn AccuWeather meteorologists.

"A cool Canadian high pressure system building into the Midwest will bring the risk of a frost or freeze Monday morning," said AccuWeather Senior Meteorologist Dan Pydynowski. The Detroit and Pittsburgh metropolitan areas are among those where temperatures can fall close to or below freezing Monday morning.

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A frost can occur when air temperatures are even a few degrees above freezing, but for a freeze to occur, temperatures need to fall to or below 32 degrees Fahrenheit. The presence of or absence of a breeze or atmospheric moisture can also be determinative of whether a frost or freeze occurs, but AccuWeather is concerned a widespread area can deal with issues Monday morning.

"If you started your plants in pots, it would be a good idea to bring them indoors the next couple of nights," said Pydynowski. "If you are not able to do so, cover up your veggies and flowers with a blanket or tarp to protect them from a frost or freezing temperatures."

For vineyards and orchards where damaging freezes can mean a huge economic impact, steps for precautions to protect against the cold are a bit more complicated. Large fans and sprinkler systems are among the mitigation efforts that may have to be utilized to protect the valuable vegetation.

Following a brief return to more seasonable temperatures later on Monday and on Tuesday from the Midwest to the Northeast, another cold front will bring a renewal of frost and freeze concerns during the middle of this week, say AccuWeather meteorologists. This time around, temperatures can be even lower and more locales can experience a freeze versus just a frost.

On Wednesday night and early Thursday morning, temperatures as far south as the southern Appalachians and as far east as interior New Jersey and coastal New England can drop into the lower-30s and even 20s for a few hours. Such widespread freezing temperatures can be hard to guard against, but there are glimmers of hope ahead beginning later in the week and to close out April.

"Fortunately, since it is still only April, if you do suffer any damage to sensitive vegetation, there is plenty of time to replant and enjoy the remainder of the spring," added Pydynowski.

AccuWeather's team of long-range forecasters are expecting warmer-than-average air for the last few days of April and into the start of May. Historically, the last frosts and freezes occur during this time frame in the lower Midwest across the mid-Mississippi and Ohio Valleys and into the interior mid-Atlantic, so many areas here would then have the green light to hit the ground running with spring planting.

"Any frost potential in May is likely to be marginal and highly localized," said AccuWeather Senior Meteorologist Alex Sosnowski.

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