After a week of warmth, Environment Canada is forecasting another balmy, sunny weekend.

Many patios across the GTA have already opened in preparation for St. Patrick's Day weekend, and green beer enthusiasts will not be disappointed.

Friday's high of 19 C broke the record of 18.3 C set in 1945. The normal high for March 16 is only 5 C.

For Saturday, Environment Canada predicts a high of 15 C. Fog that's developing overnight Friday should thin out early in the morning.

Saturday night will dip down to 8 C, but the average low for March is - 4 C.

Sunday will be cloudy but even warmer, with a high of 20 C, according to Environment Canada.

While the warm weather is good news for St. Paddy's Day revellers, it also means that Ontario may be paying Quebec to take its excess energy in coming days.

With the predicted high temperatures, Ontario residents aren't using energy for heating, and it's not quite warm enough to turn on the air conditioning, either.

The result is a glut of energy on the grid that has to go somewhere.

On a normal March weekend, the province would require about 12,000 megawatts of power, but it is estimated that the province will only need 11,000 MW because it's so warm.

This means there will be about 1,000 MW too much on the grid, enough to power the cities of London and Hamilton combined.

As well as paying Quebec to take the excess energy, the province may also pay Bruce Power to make steam. The power plant can't shut down nuclear reactors when energy needs decrease, so turning the excess energy into steam and bypassing the energy grid is the only option.

It will also be a good weekend to see Niagara Falls, and not just because of the warm weather.

Ontario Power Generation will likely make water levels higher, as it shuts down tunnels that usually divert millions of litres of water from above the falls, to below.

With files from Paul Bliss