Montreal’s weather is warming up but here’s why you shouldn’t leave your plants out (yet)

Spring may be here, but Montreal’s weather isn’t fully cooperating (especially at night).If you’ve been playing the daily game of moving your potted plants from the balcony to the living room and back again, you’re not quite done yet.

A frost risk is in the forecast for parts of southern Quebec overnight Monday into Tuesday, and Montreal isn’t as safe as it might seem.

According to a new report from MétéoMediaMedia, the city is expected to see a low of 2°C tonight, but with wind chill it will feel like 0°C. That’s a problem for anyone with annuals or tender vegetables outside, since those plants can’t tolerate temperatures below 10°C. If they’re out tonight, bring them in.

The regions with an outright frost risk include Outaouais, Estrie, Centre-du-Quebec, Beauce, the Quebec City area, Mauricie, Lanaudiere and especially the Laurentians. As MétéoMedia meteorologist Bertin Ossonon notes, it could drop as low as -4°C in Mont-Tremblant overnight.

Clear skies will make things worse across the board. Cloud cover normally acts as a kind of blanket, trapping warmer air near the ground. Without it, that warmth escapes and temperatures can fall faster than the forecast suggests.

For hardier plants in regions where lows stay above -2°C, watering just before nightfall should be enough protection. But for annuals and tender vegetables anywhere in the province, tonight is not the night to leave them outside and hope for the best.

Most vegetable seedlings are still indoors in pots anyway. Transplanting them outside will have to wait just a little longer.

A May frost in Montreal is actually pretty rare

Montreal has a bit of a buffer compared to the rest of the province. According to MétéoMedia, a frost this late in May has only happened twice in the past 15 years on the island, and the city’s average last frost date is April 27.

But you don’t have to go far for that to change. Less than 50 kilometres north in Mirabel, the last frost of the season has landed a full month later than Montreal’s on two separate occasions in the past five years. The island’s heat bubble is real, and it makes a bigger difference than most people realize.

Warmer nights are coming

As for this week’s forecast, Tuesday night will still be on the cooler side, but after that, MétéoMedia says overnight lows in Montreal are expected to climb back toward seasonal norms. The average overnight low this time of year sits around 13°C, and the two-week outlook shows minimums ranging between 8°C and 13°C for the city. The indoor-outdoor shuffle should be behind you very soon.

Here’s what the rest of the week looks like

Tuesday is actually a nice day, with a mainly sunny morning and a mix of sun and clouds in the afternoon, highs around 14°C. Rain moves in Wednesday afternoon and sticks around into Thursday, with highs of 17°C and 15°C respectively. Friday stays unsettled with light rain and highs around 18°C.

Then the weekend finally delivers. Saturday brings a mix of sun and clouds, a high of 20°C and only a chance of a shower. Sunday looks like the pick of the week, with sunny skies from morning through evening and highs hitting 20°C.