By Wynne Parry, LiveScience Senior Writer:

The planetary warm spell continued through June; last month ranked as the fourth warmest June since record keeping began in 1880, according to the U.S. National Oceanographic and Atmospheric Administration.

Much of the world saw higher-than-average temperatures for June, particularly the lower 48 states, where last month brought the warmest 12-month period since the late 19th century. In addition to most of North America, Eurasia and northern Africa also saw much higher-than-average monthly temperatures, according to NOAA.

Only Australia, northern and western Europe, and the northwestern United States were notably cooler than average, NOAA reported. (In the United States, this year's heat wave has been confined to the eastern two-thirds of the country.) Christchurch, New Zealand, where it is winter, had its coolest daily maximum temperatures in more than 130 years of national recordkeeping.

Globally, April and May 2012 ranked in the top 10 for average warmth, while March, February and January all made the top 25 since 1880.

June 2012 was the 328th consecutive month with a global temperature above the 20th century average.

As of July 3, 56 percent of the continental United States was experiencing drought conditions — this marks the largest area affected by drought in the 12-year record kept by the U.S. Drought Monitor. Drought was not universal. The United Kingdom had its wettest June since national record keeping began in 1910 and Stockholm, Sweden, had its wettest June ever since 1786, according to NOAA.

Since weather has natural ups and downs, climate scientists resist attributing extreme events, such as a severe storm or heat wave, or even short-term weather, such as an unusually hot season or year, to human caused-climate change. However, they also note, temperature records reveal a long-term trend for warming that has been picking up speed. For example, the first decade of this century was the warmest on record, according to NOAA's State of Climate in 2010 report.

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