An "extreme weather alert" has been issued for Vancouver's homeless.

"Conditions are sub zero and they really pose a real health and safety risk and we want people who are living outside to come in to the designated shelter sites."

Irene Jaakson, coordinator of the city's extreme weather response program, says the alert is in place for the next three nights.
She adds it opens up additional space in shelters.
 
"Across all of our sites, we're looking at about 200 extra mats.  But I really need to stress that we have not turned anybody away, I'm certainly cautiously optimistic that we're not going to have to turn anybody away."

The forecast calls for a low of minus three tonight.