Ottawa is in for a sharp weather turnaround today, with a mostly cloudy start giving way to a messy mix of rain and snow before temperatures tumble hard tonight. The city is currently sitting at -3°C, with a RealFeel of -1°C under mostly cloudy skies. Winds remain light from the northeast at 3 km/h, with gusts near 6 km/h, while air quality is rated fair. On the surface, that may not sound too dramatic early in the day, but the broader forecast tells a much bigger story for residents heading into the evening.
The key weather shift comes later, when daytime temperatures that climb as high as 6°C are expected to crash to -11°C overnight. That kind of swing can quickly change how roads, sidewalks, driveways, and neighbourhood streets feel across Ottawa. Wet daytime conditions may seem manageable at first, but once colder air moves in and rain begins turning to snow, surfaces can become more slippery and uncomfortable in a short period of time.
Ottawa Starts Cold but Relatively Calm
This morning begins on a quieter note. Ottawa is mostly cloudy, with temperatures near -3°C and a RealFeel around -1°C. Winds out of the northeast are light at 3 km/h, with gusts reaching 6 km/h, which means the city is not dealing with a major wind-driven weather event early on. Air quality is described as fair, adding another layer of context for residents planning to be outside. Overall, the first half of the day looks cold but manageable, especially compared with what is expected later tonight.
The hourly trend also points to a gradual warm-up through the day. Morning readings move from roughly -1°C toward 3°C, before the afternoon peaks around 6°C. That warming pattern is important because it sets up the rain-and-snow mix that Ottawa is expected to see during the day. While temperatures improve temporarily, the atmosphere remains unstable enough to keep precipitation in the picture.
Snow and Rain Mix Through the Day
For much of today, Ottawa is expected to stay under thick cloud cover with periods of snow and rain. This is not shaping up to be a major daytime snow accumulation event. In fact, little to no accumulation is expected while temperatures are milder. That detail matters because it may leave many people thinking the weather risk is limited. Roads may simply look wet, slushy, or uneven instead of fully snow-covered.
Still, this type of forecast often becomes more disruptive later because the city spends the daytime collecting moisture on surfaces without seeing much buildup. Streets, sidewalks, transit stops, parking lots, and residential areas can remain damp through the warmer part of the day. Once the temperature begins to fall, that wet layer can quickly become more of a concern than the daytime snowfall itself.
Temperatures Crash Tonight as Rain Turns to Snow
The biggest forecast detail is the overnight reversal. Ottawa is expected to shift from a comparatively mild afternoon into a much colder, breezier night. Rain is forecast to change to snow as temperatures plunge from the daytime high of 6°C to an overnight low of -11°C. That is a sharp drop, and it is exactly the kind of pattern that can make weather conditions feel much worse after sunset than they did during the afternoon.
Evening and nighttime conditions are expected to turn breezy and colder, with snow and flurries moving in as the colder air deepens. Light accumulation of up to around 1 centimetre is possible. That may not sound significant compared with a full winter storm, but in a setup like this, even a small amount of fresh snow can create extra issues when it lands on top of wet surfaces during a fast freeze.
The 13-Hour Wintercast Window Matters
Another detail that stands out is the Wintercast signal pointing to snow lasting around 13 hours, stretching from the afternoon into late night. That extended window matters because it suggests Ottawa may deal with changing conditions for much of the day rather than a short burst of weather. Residents could see one version of the forecast in the afternoon and a much different one by late evening.
This kind of prolonged weather period can affect planning in subtle ways. The morning may feel routine. The afternoon may feel wet and inconvenient but not severe. Then, by night, the city can shift into a colder and more slippery pattern with snow, flurries, and patches of refreezing moisture. The long duration makes the forecast more important than a quick glance at snowfall totals might suggest.
What Ottawa Residents Should Watch Most Closely
The most important takeaway is not just that snow is in the forecast. It is that Ottawa faces a full sequence of weather changes in a single day: a cold and mostly cloudy start, a gradual warm-up, a daytime rain-and-snow mix, little daytime accumulation, then a breezy nighttime cooldown with snow, flurries, and a temperature crash to -11°C. When weather changes in steps like this, the evening period often becomes the most uncomfortable and the most deceptive.
Morning conditions should stay cold but manageable. By afternoon, wet conditions from the rain-and-snow mix are likely to be the bigger issue. Tonight is when the forecast becomes more concerning, as slippery spots may develop due to light snow accumulation and rapidly falling temperatures. That means the practical impact may be felt most on untreated sidewalks, residential streets, parking areas, and surfaces that stay damp through the day.
Where to Follow Updates
Residents looking for official forecast updates can monitor Environment Canadaâs Ottawa forecast page for changing hourly details and alerts. For live travel conditions, closures, and disruptions, the City of Ottawa traffic map can also help residents track how conditions are evolving across the city.
For Ottawa, todayâs forecast is really about transition. The city may go from a manageable, mostly cloudy and chilly morning to a wet afternoon, then into a colder, breezier night with snow and flurries. With temperatures swinging from 6°C to -11°C, even light accumulation near 1 centimetre could have a bigger effect than it appears on paper. That is why tonightâs rain-to-snow change is the detail residents should watch most closely.
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