An unseasonably cool day is in store as a big high pressure system is parked over southern Quebec at the moment. Despite lots of sun the temperature is only going to reach 45 or so. The dry ground, low humidity and a gusty northerly wind will cause any brush fires to spread rapidly so be careful if you're playing with a flamethrower in Prospect Park. Clear skies are expected again tomorrow but it shouldn't be quite as cool or windy. Look for Thursday's high to be near 50 degrees.
The high pressure system will move eastward and lose its grip on the region starting Friday. An upper-level trough is expected to deepen as the surface high moves away and that should produce a low pressure system that will drag through the Great Lakes region. That will bring us a cloudy and warmer Friday with a high in the low 50s. We could see some light rain from Friday night into Saturday.
That should give everyone enough warning to get your union suits ready for Sunday because it is going to be brisk. Sunday's high looks to be in the mid to upper 30s and Monday morning's low could dip into the mid 20s. After another cold day on Monday there looks to be some mid-week warming and rain but it's too early to say with any certainty.