Snow may have finally arrived in the Ottawa-Gatineau area, but police are warning that it's still too early to safely use the region's rivers and lakes for recreational activities like snowmobiling and ice fishing.

"We haven't had that good freeze-over for the ice on the lakes yet," said Sgt. Byron Newell with the Ontario Provincial Police's Snowmobile and All Terrain Vehicle Enforcement Unit.

"It's not safe to be out on the lakes at this time."

On Dec. 29, a record 26 centimetres of snow blanketed the city's streets. According to Environment Canada data, an additional 4.6 centimetres fell on New Year's Day, and snow was in the forecast for much of Sunday, too.

However, the fact local bodies of water have iced over enough to become snow-covered doesn't mean they're necessarily safe to traverse, said Newell.

Clear ice good, opaque ice bad

"You want nice, clear, blue or black ice. If it's opaque at all, that means there's a snow freeze on the ice, which makes the ice more dangerous and weak," Newell said.

An angler pulls some fishing gear out on the ice

Ontario Provincial Police say the ice around Ottawa is still too thin to safely use for ice fishing, snowmobiling and other recreational activities. (Patrick Record/The Ann Arbor News/Associated Press)

"And also, if it's gray at all, that means there's water present and it's very unsafe at that point."

The temperature is expected to plummet tonight, however. Environment Canada is forecasting an overnight low of - 20 C, and as a result Ottawa Public Health has issued its first frostbite advisory of the winter.

Consult bait shops, resorts first

That said, the temperature is expected to rise once again to just below freezing later in the week, and Newell says you need a "progression" of cold days before that thick, hard ice develops.

Anyone who's hoping to eventually venture onto the ice should consult with local bait shops and resorts about its thickness first, as well as check the Ontario Federation of Snowmobile Clubs website, said Newell.

The "general rule of thumb" is that you want 12.5 centimetres (5 inches) of clear ice before heading out, but even that's not a hard and fast rule, Newell said.

"Ice is never 100 per cent safe," said Newell.