Folks, we’re looking at a classic April overnight setup across Southwestern Ontario. The mercury is sitting between -3°C and +1°C right now, with winds making it feel closer to -7°C in spots like Sarnia. If you’re heading out tonight, bundle up because that wind chill isn’t messing around.

What’s interesting is how we’ve got this east-west temperature split happening. Windsor and Leamington are sitting pretty at 1°C thanks to Lake Erie’s moderating influence, while our inland areas like London and Sarnia are dipping below freezing. Classic lake effect at work here.

Tonight Into Wednesday Morning

We’re tracking clear skies for most of the overnight, which means radiational cooling is going to drop us down to around -4°C by dawn. That’s cold enough for frost on windshields and potentially icy spots on untreated surfaces. The good news? Winds are backing off to just 6-11 km/h, so the brutal wind chill we’re feeling now will ease up.

By 6 AM, we’re looking at -4°C feeling like -8°C with those southeast winds picking back up. School bus parents, give yourself extra time for scraping ice and warming up the car.

Wednesday’s Turnaround

Here’s where things get interesting, weather nerds. We’ve got a significant warm-up brewing as southerly flow takes over. By noon Wednesday, we’re jumping to 7°C with increasing southeast winds up to 24 km/h. That’s a massive 11-degree swing from the morning low.

The HRDPS and GFS models are in agreement on this rapid temperature rise, driven by warm air advection ahead of our next system. But don’t get too excited about spring weather just yet.

The Week Ahead

Thursday brings our first real rain threat with 29 km/h winds and light drizzle moving in. Nothing too dramatic, but enough to make the roads slick during the morning commute.

Friday is where I’m keeping a close eye on things. We’re tracking a more substantial system that could dump over 12mm of rain with a 68% chance of showers. That’s legitimate soaking rain, folks. Basement check time if you’ve had water issues before.

The weekend looks like a typical April roller coaster – from near-freezing Saturday morning to 16°C by Sunday afternoon.

What You Need to Know

Tonight: Dress for winter. We’re talking -4°C with potential frost and icy spots on bridges and overpasses. Give yourself extra time tomorrow morning for vehicle prep.

Wednesday commute: Start cold but warming fast. Layers are your friend because by afternoon you’ll be shedding that winter coat.

This weekend: Keep the umbrella handy Friday, but Saturday and Sunday are looking decent for any outdoor plans you’ve been putting off. Just typical April unpredictability.

The models are showing good agreement through Thursday, but there’s some divergence in the weekend pattern. I’ll be watching how the Euro handles that Sunday system compared to the GFS. Stay tuned.