Jeff Privette describes the challenges of using satellites that people designed for observing changes in the weather from day to day to study changes in climate from decade to decade.

Anthony Arguez, Normals Program Manager at NOAA’s National Climatic Data Center explains what scientists mean when they compare current weather conditions to “normal.”

In early July 2012, conditions throughout most of the contiguous 48 states ranged from abnormally dry to exceptional drought.

The average global temperature for June 2012 was the fourth highest for any June since record keeping began in 1880. Land-only surface temperatures were the highest on record for the month. June 2012 also marks the 36th consecutive June and 328th consecutive month with a global temperature above the twentieth-century average. The last June with below-average global temperatures was June 1976.

Data from 2010 indicate that mountain glaciers predominantly lost mass, and preliminary data from 2011 indicate a continuation of the same long-term trend.

In early 2011, stratospheric temperatures rose over the tropics due to La Nina while temperatures over the poles fell below the long-term average.

In 2011, annual snow cover extent over Northern Hemisphere continents (including the Greenland ice sheet) averaged 24.7 million square kilometers, which is 0.3 million square kilometers less than the long-term average.

In 2011, La Niña and the Pacific Decadal Oscillation cooled parts of the Pacific Ocean, but unusually warm temperatures predominated elsewhere.

Except for some La Niña-cooled regions of the tropical Pacific and a few other cool spots, the upper ocean held more heat than average in 2011 in the Pacific, Atlantic, Indian, and Southern Oceans.

In 2011, Earth’s atmosphere was cooler and drier than it had been the previous year, but it was more humid than the long-term average.