Toronto's weather can't make up its mind this week. After a mild run-up to Halloween with daytime highs in the mid-to-upper teens, the city dipped close to freezing on Monday night, with the thermometer bottoming out at 2°C — cold enough that Environment Canada issued a yellow frost advisory warning of potential damage to plants, trees, and crops.

Tuesday stays chilly despite the sunshine, topping out at 11°C with an overnight low of 6°C. But things turn around quickly. Wednesday climbs to 16°C, and Thursday is the standout: a low of 9°C and a high of 21°C — a swing of 19 degrees compared with Monday night, more like early September than late October. The catch? There's a chance of showers on Thursday, with rain more likely after dark.

The good news for anyone planning costumes and doorbells: Halloween itself looks dry. Friday brings sunny skies and a high of 16°C, and Saturday — the big day — should be cloudy but manageable, with a high of 14°C and a mild overnight low of 10°C. No umbrella needed for trick-or-treating, based on current forecasts.

Looking further ahead, the Old Farmer's Almanac long-range outlook for southern Ontario suggests November will start sunny and warm, then turn showery in the southeast between November 7 and 11. A stretch of sunny but chilly weather follows through mid-month, before possible snow moves in between November 18 and 22. The month should end with rain, mild temperatures, then flurries and colder air. On balance, the Almanac expects an average temperature of 4.5°C for southern Ontario — a degree above normal in the east and a full four degrees above in the west — with total precipitation of about 45 mm, well below the usual 70 mm.

Why does this matter to travellers? If you're heading to Toronto in the next few days, pack layers rather than full winter gear. A frosty night can be followed by a 21°C afternoon, so a light jacket you can stuff in a bag is the smart move. And if you were weighing a late-October city break against a November one, the forecast hints at a milder-than-usual start to November — though the third week could bring the season's first snow.

For locals, the frost advisory is a reminder to protect anything tender in the garden before Wednesday's warm-up arrives, and to enjoy the summer flashback on Thursday while it lasts.