El Nino has brought an extremely mild winter so far
The Northern half of North America has benefitted from great weather in November and December because of El Nino.
The US climate prediction centre is out with their latest and say they expect El Nino to remain strong throughout the Winter and then taper off in the Spring/Summer.
The Fed has blamed harsh weather for disappointing Q1 growth for the past two years. If mild temperatures continue, it may boost growth early in 2016 at a time when the Fed want/expects to see a pickup. That could lead to another rate hike early in Q2 in what could prove to be a mistake.