Remember the record snowfall this winter in Boston and surroundings? It seemed endless. The record total for Boston was 108.6 inches. This image is from early February.
This map from NOAA shows liquid precipitation over the region for the recent 180 days since late November 2014. There are widespread locations with 20 inches. One in yellow near Boston had over 25 inches.
Things have changed. For the past 30 days, the same region is very dry with about 0.5 inches of precipitation. That is much below normal.
What about Alaska and northern Canada? Between May 17-24, that region had record warmth. This map from NASA Earth Observatory shows the deviation from the 2001-2010 average for the same dates. The darkest reds are up to 12 C˚ (22 F˚) warmer. Fairbanks had a high of 85˚F in that period of time.
One reason is a large buckle in the jet stream. I drew in green the path of the jet for May 20. It arced up to Alaska, back down to the Pacific, west of California, where there is unusually warm water. It then crossed the central U.S. A large stationary High was bringing warm Pacific air into the region from the Pacific with the clockwise circulation. Also shown is a Low pressure system in the southwest states. These lows formed each of the past several weekends and tracked slowly across with the jet.
As the lows tracked across, they caused huge amounts of rainfall in the Oklahoma and north Texas areas. The following map from NOAA shows the precipitation for the past 30 days. Normal is from 3 to 5 inches. Some places have six times normal amounts. The most recent heavy rains caused deaths and damage from great flooding in the Houston, Texas area.
What about the globe as a whole? I quote from NOAA National Climatic Data Center, State of the Climate: Global Analysis for April 2015. Not good to set records here. Emphasis is mine.
The year-to-date global land surface temperature was 1.48°C (2.66°F) above the 20th century average. This was the highest for January–April in the 1880-2015 record, surpassing the previous record of 2007 by 0.03°C (0.05°F). The average global ocean surface temperature for January–April was the second highest in the 136-year period of record, at 0.55°C (0.99°F) above average, trailing 1998 by 0.02°C (0.04°F). Record high temperatures in much of the northeast to central equatorial Pacific, along with large parts of the western equatorial Pacific, contributed to the overall record warmth.
The record high equatorial Pacific temperatures have spawned earlier typhoons and stronger ones than ever before. At this early date, there have been 5 category 5 typhoons. Fortunately, forecasters are predicting a quieter than normal Atlantic hurricane season this year.