January 1
edit1918: The Australian Bureau of Meteorology formally commenced operations.
January 2
edit1960: The highest temperature in Australian history, 50.7 °C (123.3 °F), was recorded at Oodnadatta, South Australia.
January 3
edit1999: A blizzard began dropping snow on the Midwestern United States, eventually disrupting travel and causing record low temperatures from Illinois to Ontario and Quebec.
January 4
edit1841: The steamship SS Thames wrecked in a severe winter storm in the Isles of Scilly southwest of Cornwall, England, killing 61 of the 65 passengers.
January 5
edit1998: Cyclone Susan reached peak intensity as a Category 5 storm on the Australian cyclone scale it approached Vanuatu.
January 6
edit1996: The Blizzard of '96 began pounding the Eastern United States, and would eventually dump 2–4 feet (0.61–1.2 m) of snow on an area from Tennessee to Massachusetts.
January 7
edit1987: A major cold snap began in the United Kingdom and Ireland, bringing temperatures as low as −23.3 °C (−9.9 °F) and up to 75 centimetres (30 in) of snow.
January 8
edit1988: Typhoon Roy passed near Majuro atoll, Marshall Islands, causing moderate damage across the island chain and killing one person.
January 9
edit1998: Cyclone Katrina, a long-lived South Pacific tropical cyclone that meandered east of Australia for more than three weeks, reached peak intensity northwest of Vanuatu, with 1-minute maximum sustained winds of 165 km/h (105 mph).
January 10
edit1973: A devastating tornado, the deadliest in South American history, killed 54 people in San Justo, Santa Fe, Argentina.
January 11
edit1898: A tornado killed 55 people in Fort Smith, Arkansas overnight. This is tied for the deadliest tornado in Arkansas state history.
January 12
edit2006: Cyclone Tam passed near Niuafoʻou, Tonga, but little damage was reported. The previous day, the storm dumped 293.2 millimetres (11.54 in) of rain on Rotuma, Fiji in just 24 hours, a record for the island.
January 13
edit1982: Air Florida Flight 90 crashed into the Potomac River as a result of severe icing in a snowstorm, killing 78 people.
January 14
edit1888: A severe cold wave associated with a blizzard two days earlier reached its peak. The temperature reached −65 °F (−54 °C) at Fort Keogh in Montana, the second lowest temperature ever recorded in the Contiguous United States.
January 15
edit1968: A major extratropical storm struck the northern United Kingdom, bringing winds of up to 134 miles per hour (216 km/h) that damaged more than 70,000 homes in Glasgow alone. At least 28 people were killed.
January 16
edit1362: An unprecedented storm surge in the Netherlands resulted in Grote Mandrenke, Dutch for "Great Drowning of Men": at least 25,000 people were killed.
January 17
edit1706: Benjamin Franklin, who would invent the lightning rod and introduce revolutionary concepts to meteorology, was born in Boston, Massachusetts.
January 18
edit1993: An avalanche killed 59 people in Bayburt Province in northeastern Turkey.
January 19
edit1996: The remnants of Cyclone Bonita passed westward over Angola and into the South Atlantic Ocean. Bonita is the first known tropical cyclone to have its remnants affect this area.
January 20
edit2011: Elektro-L No.1, a Russian weather satellite, was launched into geostationary orbit.
January 21
edit2006: The International Cloud Experiment, a scientific expedition to gather information on cirrus clouds in the tropics, began.
January 22
edit2016: A major blizzard began to affect the Mid-Atlantic region, ultimately resulting in all-time record snowfalls for a large portion of the United States.
January 23
edit1862: The capital city of California was temporarily moved from Sacramento to San Francisco, due to the former city being entirely inundated by the worst flooding in recorded history.
January 24
edit1997: Cyclone Gretelle made landfall near Farafangana, Madagascar, killing 152 people.
January 25
edit2008: The first in a series of winter storms impacted China, beginning what would be China's most severe winter in half a century.
January 26
edit1967: A major blizzard dumped 23 inches (58 cm) of snow in Chicago, a record amount for a single storm.
January 27
edit1998: Cyclone Les caused record flooding in Katherine, Northern Territory, Australia, killing 3 people.
January 28
edit2004: Cyclone Elita made its first of three landfalls on Madagascar.
January 29
edit1984: Tropical Storm Domoina, a day after making landfall in Mozambique, began bringing record rainfall that would eventually total more than 900 millimetres (35 in) to Swaziland (since 2018 renamed to Eswatini) and parts of South Africa.
January 30
edit1916: The Sweetwater Dam in San Diego County, California was overtopped due to severe flooding.
January 31
edit2019: The state of Illinois measured its coldest temperature on record: −38 °F (−39 °C) in the town of Mount Carroll. This was part of a major outbreak of cold weather across central North America which lasted for several weeks.