January 10 – A fire destroys Lloyd's Coffee House and the Royal Exchange in London.
January 11 – At Morristown, New Jersey, Samuel Morse, Alfred Vail and Leonard Gale give the first public demonstration of Morse's new invention, the telegraph.
January 21 – The first known report about the lowest temperature on Earth is made, indicating in Yakutsk.
January 23 - A 7.5 earthquake strikes the Romanian district of Vrancea causing damage in Moldavia and Wallachia, killing 73 people.
February 6 – Boer explorer Piet Retief and 60 of his men are massacred by King Dingane kaSenzangakhona of the Zulu people, after Retief accepts an invitation to celebrate the signing of a treaty, and his men willingly disarm as a show of good faith.
February 17 – Weenen massacre: Zulu impis massacre about 532 Voortrekkers, Khoikhoi and Basuto around the site of Weenen in South Africa.
February 24 – U.S. Representatives William J. Graves of Kentucky and Jonathan Cilley of Maine face each other in a duel with rifles at 80 yards near Bladensburg, Maryland. On the third attempt, Congressman Cilley is fatally wounded and bleeds to death.
March 13 – A combination of rain and melting snow causes the Danube River to overflow its banks, washing away villages in western Hungary and inundating the twin cities that become Budapest. More than 150 people are drowned and Europe's nations come to Hungary's aid to prevent the spread of famine and disease.
March 31 – The first installment of Nicholas Nickleby, the new novel by Charles Dickens, is released as the opener of a 20-part serialization in London.
April 4 – 22 – The paddle steamer makes the transatlantic crossing to New York from Cork, Ireland in 18 days, though not using steam continuously.
April 8 – 23 – Isambard Kingdom Brunel's paddle steamer (1838) makes the transatlantic crossing to New York from Avonmouth, England, in 15 days, inaugurating a regular steamship service.
April 30 – Nicaragua declares independence from the Federal Republic of Central America.