A New Month, But Cool Weather Persists

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When the only complaint you have about a month of New England weather is that it's been on the cool side, you're doing alright. After an easy winter that featured many warm spells and plenty of breaks between the flakes, spring has come along at a slow pace. This actually happens a lot. When exiting an El Nino winter, we often wind up with a cool stretch in spring. This one hasn't been particularly noteworthy - just about a degree below average and middle of the pack so far as overall rankings go - but it was enough to end a long streak. April is the first month of below average temperatures in Boston since last June!

Departures from average this April across the Northeast. While cool in Boston, it's actually been more unusually cool across northern New England and Upstate New York. Source: Northeast Regional Climate Center

On the plus side, it hasn't been dreary and cool. We've had plenty of sunshine. The cause of our coolness has been a combination of a major early-month cold shot and a lot of ocean influenced days/lack of land breezes. You can't warm up much around here in spring without a good push of westerly winds, and those days have been few and far between. Looking ahead there aren't many of them, either. So no rush to change out the cool-season wardrobe - it will be getting some more use before getting buried in the closet until fall.

A cool rain develops during Sunday from west to east. Should be rather raw and wet by the evening region-wide.

May 1st won't be winning any awards as we turn the calendar page. As clouds thicken and showers move in, temps will only manage the upper 40s and low 50s - a solid 10 to 15º below average. And more onshore (northeast) winds will keep us stuck in the 40s on Monday with areas of showers and drizzle. In fact, this first week of May isn't going to offer too many chances to bask in warm sunshine. A deep eastern trough is expected to set up shop and then cut-off for a time later this week, producing a lot of onshore wind and a rather unsettled pattern.

Euro EPS has been showing this deep eastern trough for a long time now, which should help an area of low pressure sit along the East Coast for much of late-week and perhaps next weekend too. Source: Weatherbell

While the exact position of low pressure is still a little uncertain, this type of setup isn't conducive to warming - especially near the coastline. We may get a nice break on Tuesday and if we're lucky, lasting into Wednesday. But in general the theme should be for onshore winds and below average temperatures through Mother's Day Weekend. It should also help deliver some beneficial rain to make sure spring plants get off to a good/healthy start. Chances for rain exist on Sunday, Monday, *maybe* Wednesday, Thursday, Friday, and Saturday. All told I'm hopeful we'll manage an inch or more before the week is done.

So when will we warm up? And when is it safe to garden? As it looks right now, I wouldn't expect any sustained warmth (which we'll say is temps at or above 70º) through mid-May. After that, there are some signals that we'll be able to pull out of this and start a legitimate warm-up. But I'm definitely not thinking we'll see anything like last May, which was one of the warmest and driest on record across the region.

Chilly or not, spring is in bloom in Boston! Photo: Eric Fisher

When it comes to the garden, cold crops are in good shape. Your typical early season plants like asparagus and peas can handle cold, and it's a good time to start thinking about leafy greens (especially those you can bring in or cover up on especially cold nights). Even though we've been on a cool stretch, many of our trees are showing signs of life. Eventually, daylight wins out. Many of these late spring bloomers or trees respond more to length of daylight than they do temperature. So even when it stays cool, they start to come out. May is the month of green here in southern New England and we'll still be decked out in fresh vibrant foliage within a couple of weeks.