Which of the following contributed to the Chicago Fire according to historical accounts?

The Chicago Fire of 1871 was significantly exacerbated by the presence of wooden structures closely built together. Many buildings in Chicago at that time were constructed of wood, which is highly combustible, and they were packed tightly in urban areas. This close proximity allowed flames to spread quickly from one building to another, creating a disastrous situation as the fire consumed large portions of the city in a very short time.

The building materials and urban design made the fire particularly dangerous, as wooden buildings lacking adequate spacing become fire hazards, especially when a fire ignites. Historical accounts point to these conditions as critical factors contributing to the fire's rapid escalation and the difficulty of controlling it.

The other options do not present conditions that contributed to the fire in the same direct manner. For instance, well-organized fire departments would typically help in controlling blazes, and heavy rainfall prior to the fire would likely have dampened the risk rather than increased it. Similarly, low temperatures would also not be conducive to the rapid spread of fire, as colder conditions typically slow down the ignition of materials.