Query: Days of near-100-degree-Fahrenheit temperatures cooked the Mountain West in early July, and a scorching heat wave lingered over the Pacific Northwest in early August.”

Relevant passages:
Cold wave <=SEP=> A cold wave ( known in some regions as a cold snap ) is a weather phenomenon that is distinguished by a cooling of the air . Specifically , as used by the U.S. National Weather Service , a cold wave is a rapid fall in temperature within a 24-hour period requiring substantially increased protection to agriculture , industry , commerce , and social activities . The precise criterion for a cold wave is determined by the rate at which the temperature falls , and the minimum to which it falls . This minimum temperature is dependent on the geographical region and time of year .   In the United States , a cold spell is defined as the national average high temperature dropping below 20 F.

2010 Northern Hemisphere heat waves <=SEP=> The 2010 Northern Hemisphere summer heat waves included severe heat waves that impacted most of the United States, Kazakhstan, Mongolia, China, Hong Kong, North Africa and the European continent as a whole, along with parts of Canada, Russia, Indochina, South Korea and Japan during May, June, July, and August 2010. The first phase of the global heatwaves was caused by a moderate El Niño event, which lasted from June 2009 to May 2010. The first phase lasted only from April 2010 to June 2010, and caused only moderate above average temperatures in the areas affected. But it also set new record high temperatures for most of the area affected, in the Northern Hemisphere. The second phase (the main, and most devastating phase) was caused by a very strong La Niña event, which lasted from June 2010 to June 2011. According to meteorologists, the 2010–11 La Niña event was one of the strongest La Niña events ever observed. That same La Niña event also had devastating effects in the Eastern states of Australia. The second phase lasted from June 2010 to October 2010, caused severe heat waves, and multiple record-breaking temperatures. The heatwaves began on April 2010, when strong anticyclones began to develop, over most of the affected regions, in the Northern Hemisphere. The heatwaves ended in October 2010, when the powerful anticyclones over most of the affected areas dissipated. The heat wave during the summer of 2010 was at its worst in June, over the Eastern United States, Middle East, Eastern Europe and European Russia, and over Northeastern China and southeastern Russia. June 2010 marked the fourth consecutive warmest month on record globally, at 0.66 °C (1.22 °F) above average, while the period April–June was the warmest ever recorded for land areas in the Northern Hemisphere, at 1.25 °C (2.25 °F) above average. The previous record for the global average temperature in June was set in 2005 at 0.66 °C (1.19 °F), and the previous warm record for April–June over Northern Hemisphere land areas was 1.16 °C (2.09 °F), set in 2007. The strongest of the anticyclones, the one situated over Siberia, registered a maximum high pressure of 1040 millibars. The weather caused forest fires in China, where three in a team of 300 died fighting a fire that broke out in the Binchuan County of Dali, as Yunnan suffered the worst drought in 60 years by February 17. A major drought was reported across the Sahel as early as January. In August, a section of the Petermann Glacier tongue connecting northern Greenland, the Nares Strait and the Arctic Ocean broke off, the biggest ice shelf in the Arctic to detach in 48 years. By the time the heatwaves had ended in late October 2010, about $500 billion (2011 USD) of damage was done, in the Northern Hemisphere alone. The World Meteorological Organization stated that the heat waves, droughts and flooding events fit with predictions based on global warming for the 21st century, include those based on the Intergovernmental Panel on Climate Change's 2007 4th Assessment Report. Some climatologists argue that these weather events would not have happened if the atmospheric carbon dioxide was at pre-industrial levels.