January - A massive winter storm, caused by El Niño, strikes New England, southern Ontario and Quebec, resulting in widespread power failures, severe damage to forests, and numerous deaths.
January 6 - The Lunar Prospector spacecraft is launched into orbit around the Moon, and later finds evidence for frozen water, in soil in permanently shadowed craters near the Moon's poles.
January 28 - Gunmen hold at least 400 children and teachers hostage for several hours, at an elementary school in Manila, Philippines.
January 29 - In Birmingham, Alabama, a bomb explodes at an abortion clinic, killing 1 and severely wounding another. Serial bomber Eric Rudolph is the prime suspect.
February - Iraq disarmament crisis: The United States Senate passes Resolution 71, urging U.S. President Bill Clinton to "take all necessary and appropriate actions to respond to the threat posed by Iraq's refusal to end its weapons of mass destruction programs."
February 2 - The Standard & Poor's 500 index closed above 1,000 for the first time, rising 20.99 points, or 2.14%, closing at 1,001.27.
March 5 - NASA announces that the Clementine probe orbiting the Moon has found enough water in polar craters to support a human colony and rocket fueling station.
March 24 - The Jonesboro massacre, 2 young boys (aged 11 and 13 years) fire upon students at Westside Middle School while hidden in woodlands near the school. 4 students and 1 teacher are killed, and 10 are injured.
April 8 - Iraq disarmament crisis: UNSCOM reports to the UN Security Council that Iraq's declaration on its biological weapons program is incomplete and inadequate.
April 16 - An F3 tornado passes through downtown Nashville, Tennessee - the first significant tornado in 11 years to directly hit a major city. An F5 tornado travels through rural portions south of Nashville (see 1998 Nashville tornado outbreak).
April 25 - A waste reservoir at the Los Frailes mine in Andalusia, Spain ruptures, discharging heavy metal waste into the Guadiamar River. The pollution threatens the sensitive ecosystem and endangered species of Doñana National Park, Spain's largest nature reserve, but is diverted into the Guadalquivir River. Up to 100 km² of farmland are ruined by the spill. [1]
May 11 - The first euro coins are minted in Pessac, France. Because the final specifications for the coins were not finished in 1998, they will have to be melted and minted again in 1999.
May 13 - India carries out 2 more nuclear tests at Pokhran. The United States and Japan impose economic sanctions on India.
May 13–14 - Riots directed against Chinese Indonesians break out in Indonesia. Indonesian natives destroy and burn Chinese Indonesian-owned properties and kill and rape more than 1,000 Chinese Indonesians.
May 15 - Iraq disarmament crisis: UNSCOM learns that an Iraqi delegation has travelled to Bucharest, to meet with scientists who can provide the country with missile guidance systems.
May 21 - Suharto resigns, after 32 years as President of Indonesia and his 7th consecutive re-election by the Indonesian Parliament (MPR). Suharto's hand-picked Vice President, B. J. Habibie, becomes Indonesia's third president.
May 21 – September 30 - Expo '98 is held in Lisbon, Portugal, with the title "Oceans, an Heritage for the Future". UNESCO had previously declared 1998 to be the International Year of the Oceans due to the Expo, which 12 million people attended.
May 28 - Nuclear testing: In response to a series of Indian nuclear tests, Pakistan explodes 5 nuclear devices of its own in the Chaghai hills of Baluchistan, prompting the United States, Japan and other nations to impose economic sanctions.
May 30 - Nuclear testing: Pakistan conducts 1 more nuclear explosion following its first test.
June 14 - The Chicago Bulls win their 6th NBA title in 8 years when they beat the Utah Jazz, 87-86 in Game Six. This is also Michael Jordan's last game as a Bull, clinching the game in the final seconds on a fadeaway jumper.
July 17 - A tsunami triggered by an undersea earthquake destroys 10 villages in Papua New Guinea, killing an estimated 1,500, leaving 2,000 more unaccounted for and thousands more homeless.
August 7 - Yangtze River Floods: In China the Yangtze River breaks through the main bank; before this, from August 1-5, periphery levees collapsed consecutively in Jiayu County Baizhou Bay. The death toll exceeds 12,000, with many thousands more injured.
August 14 - Gary C. Evans, infamous in New York's Capital Region for killing 5 people, escapes police custody and kills himself by jumping off a bridge.
August 19 - Monica Lewinsky scandal: On the day of his 52nd birthday, U.S. President Bill Clinton admits in taped testimony that he had an "improper physical relationship" with White House intern Monica Lewinsky. He also admits before the nation that night in a nationally televised address that he "misled people" about his sexual affair with Lewinsky.
August 19 - 1998 Russian financial crisis: Russia defaults on the state short-term bonds, and devalues the ruble. The ruble loses 70% of its value against U.S. dollar in the next 6 months. Several of the largest Russians banks collapse, and millions of people lose their savings.
August 24 - First RFID human implantation tested in the United Kingdom.
August 26 - Iraq disarmament crisis: Scott Ritter resigns from UNSCOM, sharply criticizing the Clinton administration and the U.N. Security Council for not being vigorous enough about insisting that Iraq's weapons of mass destruction be destroyed. Ritter tells reporters that "Iraq is not disarming," "Iraq retains the capability to launch a chemical strike."
August 31 - North Korea reportedly launches Kwangmyongsong, their first satellite. Although North Korea reports that it reached stable orbit, NORAD was never able to confirm this assertion.
