The CW put its ratings leaders Smallville and Supernatural on hiatus for February, and originally planned to bring both series back with new episodes on March 5. The network has altered its plan, BuddyTV now reports (beware of spoilers at the link), and both shows will return on March 12 instead.

The reason for the February hiatus was that with the switch from analog to digital signal for all televisions scheduled for February 17, the networks moved sweeps (when networks set the cost of advertising spots) to March. President Obama signed the DTV Delay Act into law this week, moving the transition date to June 12. The Delay Act allows TV stations ready for the transition to proceed early; according to PC Magazine, some 700 TV stations (out of 2,000 across the country) are opting to make the switch on February 17.

BuddyTV said The CW had given no specific reason for the extra week of hiatus, and speculated that it was to avoid going up against a key night of ratings juggernaut American Idol. Which will be of little comfort to fans of the two scripted genre shows.

Smallville and Supernatural air back-to-back on Thursday nights starting at 8 ET/9 C. Smallville is in its eighth season and Supernatural is in its fourth.

Sources:
BuddyTV
PC Magazine - Obama Makes DTV Delay Official
PC Magazine - Almost 700 Stations Plan February DTV Switch