Updated 01/28/14 – 1:55 p.m.

CHICAGO (CBS) — After nearly 33 hours of temperatures below zero, Chicago got a (very) small measure of relief Tuesday afternoon, when the mercury inched back above zero.

Temperatures at O’Hare International Airport — where the city’s official temperature is recorded — had been below zero since shortly before 4 a.m. Monday, and stayed below zero until shortly before 1 p.m. Tuesday, when the temperature climbed to 2 degrees.

That might only mean taking off one of many layers of clothing you’re wearing, and even then only for a few hours, as the temperature will drop below zero again overnight. But a longer-term warmup follows Wednesday, when temperatures will climb into the teens, and possibly 20s, by the afternoon.

RELATED: Latest Conditions | NWS Advisories | School Closings | Flight Delays | Traffic | Metra Service Alerts | CTA Status Updates | Submit Photos/Video

Wednesday’s warmup will several days, as the forecast does not call for any more temperatures below zero at least through next Monday.

Though the latest extended blast of subzero temperatures was not as bad as three weeks ago, when the mercury plunged to 16 below on Jan. 6 (a record low for that date), it still led to two more days of cancelled classes for Chicago Public Schools and most other public and private school districts in the area.

Metra was warning of possible delays on Tuesday, because the extreme could cause tracks or switches to freeze. In addition, a freight train derailment in suburban Mundelein forced Metra to halt all North Central Service trains until further notice, as Canadian National Railway crews worked to get the freight train back on the tracks.

Meantime, airlines cancelled more than 600 flights at Chicago’s two airports, due to the intense cold. Airlines at O’Hare International Airport proactively cancelled more than 520 flights, while airlines at Midway International Airport cancelled at least 105 flights, according to the city’s Aviation Department.

The temperature will drop to about 4 below zero overnight, before finally rising out of the subzero range, and up to a high of about 20 on Wednesday.

After that, temperatures should remain above zero at least through next Monday.

Watch & Listen LIVE