Short answers, pulled from the story.
The Great Frost Fair on the River Thames took place in the winter of 1683. This event occurred when the river froze so solidly that people walked across it and the water became a stage for the fair. The last frost fair was held in 1814 after changes to the river made freeze-overs less likely.
The tilt of the Earth's axis at 23.44 degrees is the primary driver of winter. This tilt causes different latitudes to face the Sun differently as the planet orbits, resulting in less solar radiation reaching the Northern Hemisphere when it is tilted away from the Sun. The variation in the Earth's distance from the Sun due to its elliptical orbit is negligible compared to the effect of the axial tilt.
Ancient cultures divided the year into two seasons with winter beginning on various dates such as the 10th of November in the Julian calendar or the 1st of November in Celtic nations. In Christian Anglo-Saxon calendars, winter began on the 7th of November and ended on the 6th of February. Norsemen opened winter with the festival of Winter Nights on the Thursday between 9 and the 15th of October, while Chinese calendars marked it on or around the 7th of November.
Migratory birds and some butterflies migrate seasonally to survive winter conditions. Animals such as gophers, frogs, snakes, bats, and bears become dormant during winter and only come out when the warm weather returns. Squirrels, beavers, skunks, badgers, and raccoons store food for the winter and live on it instead of hibernating completely.
The Year Without a Summer in 1816 was caused by the eruption of Mount Tambora in Indonesia in April 1815. The cumulative effects were worldwide but were especially strong in the Eastern United States, Atlantic Canada, and Northern Europe. Frost formed in May in New England, killing many newly planted crops, and snow fell in New York and Maine in June.
Winter cold compromises the body's ability to maintain core and surface heat, leading to injuries such as hypothermia, frostbite, trench foot, and chilblains. The winter of 1794, 1795 recorded the lowest temperature ever in London at -21°F on the 25th of January. In the United States, a record five-week cold spell bottomed out at -40°F in Hartford, Connecticut and -15°F in New York City.