More than a dozen Toronto streetcars remain out of service as sub-zero temperatures are expected for the rest of the evening.

Environment Canada says the mercury is expected to dip to a low of -9 C Thursday night.

As a result of the frigid conditions, the Toronto Transit Commission says 13 streetcars are out of service.

Earlier in the day, 25 of the TTC’s aging fleet of streetcars were taken off the road. That number dropped to 13 later in the day as the mercury rose.

According to TTC spokesperson Brad Ross, the streetcars were rendered inoperable because of frozen brake lines.

To ease wait times, the TTC has replaced the streetcars with buses on the 502 Downtowner and 503 Kingston Road..