Extreme weather is weather phenomena indicative of an unstable climate; that is, weather that is at the extremes of historical patterns, especially severe or unseasonal weather.
The combination of extreme weather and high population density has led to dramatic weather catastrophes.
- January: Storm winds sweep across northern Europe, leaving at least 13 people dead and millions without electricity. (CNN) (BBC)
- August: A heat wave involving temperatures as high as 42 degrees Celsius (108 degrees Fahrenheit) struck Europe. Because summer temperatures, in much of northern Europe, rarely exceed 30 °C (86 °F), the area was unprepared for the disaster. The death toll of the heat wave has been estimated to exceed 10,000. See: European Heat Wave of 2003
- September: Hurricane Isabel makes landfall on the United States, killing at least 40 people.
- September: On September 19, about one-third of the Maili glacier broke off from the Cacausus Mountains and buried Karmadon, Russia under up to 500 feet (150 m) of ice and debris, killing 95, including the young Russian movie star Sergei Bodrov Jr.
- August: At least 109 are killed by floods caused by torrential rains in Europe, including the Malse , Blanice , and Vltava rivers of the Czech Republic, the Black Sea resort village of Shirokaya Balka near Novorossiisk in Russia (58 deaths), Germany (the Elbe and Pleisse ), and Romania. The downpours have also caused extensive damage in Austria (the Rodl and Danube), Bulgaria, Croatia, Italy, and Spain. Prime Minister Vladimir Spidla declared a state of emergency in Prague, Bohemia, Plzen and Karlovy Vary. The Elbe reached record heights in Dresden, flooding much of the city. All shipping on the Danube had to be halted. Premier Silvio Berlusconi approved $50 million in emergency aid in response to the $300 million in damage of northern Italy's crops.
- About 2000 people are killed by floods and landslides in Asia during its monsoon season.
- January: floods killed 12 and left thousands homeless in Brazil
- 15 inches (380 mm) of snow fell in Israel, the most in 50 years
February: the worst avalanches in decades prompted the governor of Alaska to declare a state of emergency
- floods killed 11 and left 20,000 homeless in the Philippines
- a tornado in Georgia kills 22
- a month of floods in Southern Africa, particularly Mozambique, kill 400 and displace 250,000
- October/November: England experiences the country's worst flooding decades after a prolonged period of heavy rain. The historic city of York and the towns of Shrewsbury, Lewes and Uckfield are among the worst hit areas. Up to 10,000 homes and businesses are affected.
- Record drought in the Northeast and Mid-Atlantic states led to declarations of emergency in six states.
- Summer: a prolonged heat wave killed 271 people in the Midwest and Northeast.
- Fall: Hurricane Floyd caused billions of dollars of damages in North Carolina
- November: a super-cyclone in Orissa, India, killed 10,000 people
- December: torrential rains and mudslides in Venezuela killed 15,000 people
- Boston experienced a record 303 consecutive days without snow, until January 13, 2000
- January: an ice storm in northern New England and Quebec left 4 million people without power, some for up to a month
- Spring: fires in Brazil and Mexico rainforests and Florida
- Summer: extreme heat waves in Texas, the Middle East and India, killed more than 4,000 people
- The worst drought in 70 years was followed by extreme floods in September in Mexico
- September: floods left 14 million people homeless in China
- October: floods left 30 million people homeless in Bangladesh