The 2013 extreme weather events included several all-time temperature records in Northern and Southern Hemisphere. The February extent of snow cover in Eurasia and North America was above average, while the extent of Arctic ice in the same month was 4.5% below the 1981–2010 average. The Northern Hemisphere weather extremes have been linked to the melting of Arctic sea ice, which alters atmospheric circulation in a way that leads to more snow and ice. By January 11, 233 weather-related deaths were reported in India. Elsewhere, particularly in Russia, the Czech Republic and the United Kingdom, low temperatures affected wildlife, delaying bird breeding and disrupting the bird migration. On January 10 Bangladesh faced the lowest temperature since country's independence, at 3.0 °C (37.4 °F) in Saidpur. While Finland and most of Northern European countries got the record high, and even the highest temperatures at Europe during May and June, Western and Middle Europe faced much cooler weather and even their wettest May and June ever. During summer prolonged heat waves in the Northern Hemisphere set new record high temperatures. On March 24, 2014, the secretary-general of the World Meteorological Organization Michel Jarraud announced that "many of the extreme events of 2013 were consistent with what we would expect as a result of human-induced climate change".
Cold spring in the Northern Hemisphere In the Northern Hemisphere, the weather pattern repeatedly directed cold Arctic air southward, leaving Greenland and northeastern Canada much warmer than average for March. High pressure situated over Greenland acted as a block, forcing the jet stream into a southerly flow. Observations over Greenland threatened to break the worldwide record for highest barometric pressure of 1083.3 mbar, set on December 31, 1968, in Siberia, the National Centers for Environmental Prediction’s Ocean Prediction Center forecast a high pressure center of at least 1074 mbar over Greenland during March. A Greenland block was also noticed during the cold weather seen in 2010. The Arctic oscillation index changed from positive to negative, weakening the pressure gradient. Throughout March the west Atlantic winds, which normally kept the winters in Europe relatively mild, have been blowing chiefly from the northeast, bringing in cold Arctic air. The westerly Atlantic winds were weakened by small air pressure difference between northern and southern latitudes. In late March, the Arctic oscillation index dropped to −5.6 and much of Northern Hemisphere experienced particularly low temperatures. The low value of the Arctic oscillation was the second lowest March value on record. The British Met Office described the cold temperatures as part of a larger-scale weather pattern in the Northern Hemisphere, associated with the negative phase of the North Atlantic Oscillation.
North America
Canada Due to expected low temperatures overnight on February 16 and 17, an extreme cold weather alert was issued in Toronto. On February 16 Environment Canada also issued a weather statement for York, Durham, Peel and Halton areas, warning of intensifying flurries. On December 22, a severe ice storm brought snow and freezing rain to Toronto, and much of Eastern Canada. The storm caused widespread power outages and left hundreds of thousands in the dark.
United States
The cold wave in the United States was influenced by a low-pressure area called a "Clipper" which brought an Arctic cold front that caused rapidly falling temperatures and strong northwest winds with gusts of 35–50 miles per hour (56–80 km/h). In January 2013, Salt Lake City had an average temperature of 19.4 °F (−7.0 °C), which became the coldest month on record since 1949 and the sixth-coldest January since 1874. On March 5 a record 6-inch snow depth was noted in Chicago's O'Hare International Airport, exceeding the previous 1999 record for that date by 2.2 inches. On the same day 900 flights were cancelled in O'Hare Airport, while Midway Airport reportedly cancelled 240 flights. U.S. Airways reported 350 flight cancellations for March 6. In Orlando, Florida, the temperature lowered to 41 °F (5 °C) on March 28, 2 degrees below the record of 1955. The lowest minimum temperature record of 1971 (51 °F (11 °C)) was also broken in West Palm Beach, Florida, where a temperature of 48 °F (9 °C) was recorded on March 28. On May 1–3, a late snow storm occurred across the central United States from Arkansas to Minnesota. The storm formed from a deep upper level trough which became a cut-off low, the event was named "Achilles" by the Weather Channel. The storm broke records for depth of snow and lateness in the season, and was cited as the worst May snow since 1947. During mid- to late-May, the tornado outbreaks of May 18–21 and May 26–31 resulted in over 100 tornadoes, including an EF5 tornado in Moore, Oklahoma, and an EF3 tornado in El Reno, Oklahoma. The related storms also resulted in record-breaking rains in North Dakota, New York, and Vermont. The tornado that went through El Reno broke the record for widest tornado ever recorded, at 2.6 miles wide. The October 2013 North American storm complex was a blizzard and tornado outbreak that affected the Northwest, Rockies, and much of the Midwest. The incident trapped over 6 dozen people inside of their automobiles and harmed 15 people in suburban Iowa and Nebraska. Rapid City, the second largest city in South Dakota, was engulfed in close to two feet of snow, which exceeds the amount of snow that the city has ever recorded during any whole month of October. Furthermore, on October 4, 2013, the city received over 1.5 feet of snow, which exceeded the previous one day record in October by more than six inches. Over 20 000 people lost electricity in Black Hills, where more than a meter of watered down, dense snow had fallen. The storm system also included thunderstorms that brought iced precipitation, significant rain and over half a dozen tornadoes to Nebraska and Iowa. Over 200 km of Interstate 90 were shut down from South Dakota to Wyoming. Tens of thousands of cattle were killed in South Dakota with ranchers reporting loss of 20 to 50% of their herds. Thousands of people were without power. Three people died in a motor vehicle accident on U. S. Route 20 in Nebraska. On December 6, a daily record snowfall of 0.1 inches (2 mm) is set in the Dallas–Fort Worth metroplex, breaking the old record of trace amounts of snow set in 1950.
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