Extended Forecast - Environment Canada
Today Chance of drizzle Max: 18°C	Sat, 18 Apr Showers Max: 21°C	Sun, 19 Apr Chance of showers Max: 7°C	Mon, 20 Apr Chance of flurries Max: 4°C	Tue, 21 Apr Chance of showers Max: 8°C	Wed, 22 Apr A mix of sun and cloud Max: 14°C	Thu, 23 Apr A mix of sun and cloud Max: 15°C
Tonight A few clouds Min: 10°C	Night Chance of showers Min: 0°C	Night Chance of rain showers or flurries Min: -1°C	Night Clear Min: -1°C	Night Chance of showers Min: 7°C	Night Cloudy periods Min: 6°C

Forecast

St. Catharines, ON (Issued: 11:00 AM EDT Friday 17 April 2026)

Today

Cloudy with 30 percent chance of drizzle near noon then a mix of sun and cloud. Fog patches dissipating near noon. High 18 except 12 near Lake Ontario. UV index 6 or high.

Tonight

A few clouds. Fog patches developing overnight. Low 10.

Sat, 18 Apr

Increasing cloudiness. Showers beginning late in the morning. Risk of a thunderstorm in the afternoon. Fog patches dissipating in the morning. Local amount 10 to 15 mm. Wind becoming southwest 30 km/h gusting to 50 in the morning. High 21. UV index 4 or moderate.

Night

Cloudy with 40 percent chance of showers. Low zero.

Sun, 19 Apr

A mix of sun and cloud with 40 percent chance of showers. High 7.

Night

Cloudy periods with 40 percent chance of rain showers or flurries. Low minus 1.

Mon, 20 Apr

A mix of sun and cloud with 30 percent chance of flurries. High plus 4.

Night

Clear. Low minus 1.

Tue, 21 Apr

A mix of sun and cloud with 30 percent chance of showers. High 8.

Night

Cloudy periods with 30 percent chance of showers. Low 7.

Wed, 22 Apr

A mix of sun and cloud. High 14.

Night

Cloudy periods. Low 6.

Thu, 23 Apr

A mix of sun and cloud. High 15.