Slash-and-burn land management, months of drought, and the passage of a strong cold front cause the Peshtigo Fire, the Great Chicago Fire and the Great Michigan Fires to break out.

Slash-and-burn agriculture is a form of shifting cultivation that involves the cutting and burning of plants in a forest or woodland to create a field called a swidden. The method begins by cutting down the trees and woody plants in an area. The downed vegetation, or "slash", is then left to dry, usually right before the rainiest part of the year. Then, the biomass is burned, resulting in a nutrient-rich layer of ash which makes the soil fertile, as well as temporarily eliminating weed and pest species. After about three to five years, the plot's productivity decreases due to depletion of nutrients along with weed and pest invasion, causing the farmers to abandon the field and move to a new area. The time it takes for a swidden to recover depends on the location and can be as little as five years to more than twenty years, after which the plot can be slashed and burned again, repeating the cycle. In Bangladesh and India, the practice is known as jhum or jhoom.

A cold front is the leading edge of a cooler mass of air at ground level that replaces a warmer mass of air and lies within a pronounced surface trough of low pressure. It often forms behind an extratropical cyclone, at the leading edge of its cold air advection pattern—known as the cyclone's dry "conveyor belt" flow. Temperature differences across the boundary can exceed 30 °C (54 °F) from one side to the other. When enough moisture is present, rain can occur along the boundary. If there is significant instability along the boundary, a narrow line of thunderstorms can form along the frontal zone. If instability is weak, a broad shield of rain can move in behind the front, and evaporative cooling of the rain can increase the temperature difference across the front. Cold fronts are stronger in the fall and spring transition seasons and are weakest during the summer.

The Peshtigo fire was a large forest fire on October 8, 1871, in northeastern Wisconsin, United States, including much of the southern half of the Door Peninsula and adjacent parts of the Upper Peninsula of Michigan. The largest community in the affected area was Peshtigo, Wisconsin, which had a population of approximately 1,700 residents. The fire burned about 1.2 million acres (490,000 ha) and is the deadliest wildfire in recorded history, with the number of deaths estimated between 1,500 and 2,500. The exact number of deaths is debated. Data from mass graves, both those already exhumed and those still being discovered, show that the death toll of the blaze was most likely greater than the 1889 Johnstown flood death toll of 2,200 people or more.