Additional info from Skeptical Science
It's easy to confuse current weather events with long-term climate trends, and hard to understand the difference between weather and climate. It's a bit like being at the beach, trying to figure out if the tide is rising or falling just by watching individual waves roll in and out. The slow change of the tide is masked by the constant churning of the waves.
In a similar way, the normal ups and downs of weather make it hard to see slow changes in climate. To find climate trends you need to look at how weather is changing over a longer time span. When we look at high and low temperature data from recent decades (Figure 1), we see that new record highs occur nearly twice as often as new record lows.
Figure 1: Ratio of record high to record low temperatures in the U.S., 1950-2009. © UCAR/Mike Shibao.
New records for cold weather will continue to be set, but global warming's gradual influence will make them increasingly rare.
Adapted from © John Cook and Skeptical Science