The Blizzards of 1888

The Schoolhouse blizzard:

The blizzard was precipitated by the collision of an immense Arctic cold front with warm, moisture-laden air from the Gulf of Mexico. Within a few hours, the advancing cold front caused a temperature drop from a few degrees above freezing to −20 degrees Fahrenheit (−40 °F in some places). This wave of cold was accompanied by high winds and heavy snow. The fast-moving storm first struck Montana in the early hours of January 12, swept through Dakota Territory from midmorning to early afternoon, and reached Lincoln, Nebraska at 3 p.m.
What made the storm so deadly was the timing (during work and school hours), the suddenness, and the brief spell of warmer weather that preceded it. In addition, the very strong wind fields behind the cold front and the powdery nature of the snow reduced visibilities on the open plains to zero. People ventured from the safety of their homes to do chores, go to town, attend school, or simply enjoy the relative warmth of the day. As a result, thousands of people—including a significant number of schoolchildren—got caught in the blizzard. The death toll was 235^[1]. Travel was severely impeded in the days following.

Followed two months later by the Great Blizzard of 1888:

The Great Blizzard of 1888 or Great Blizzard of '88 (March 11 – March 14, 1888) was one of the most severe blizzards in United States' recorded history. Snowfalls of 40-50 inches (102-127 cm) fell in parts of New Jersey, New York, Massachusetts and Connecticut, and sustained winds of over 45 miles per hour (72 km/h) produced snowdrifts in excess of 50 feet (15.2 m). Railroads were shut down and people were confined to their houses for up to a week.

Over 400 people died from the storm and the ensuing cold, including 200 in New York City alone.