Miss Maudie's house catches on fire in chapter 8 of To Kill a Mockingbird. Atticus decides to go help, and with all the ruckus caused by the whole town showing up as well, he needs to keep his children safely out of the way, but also in sight. If Atticus had left the house without waking his children first, they could have awakened, looked out the window, and become scared not knowing where their father had gone. So, for the children's well-being and peace of mind, it is better to wake them up and have them stand across the street in front of the Radleys' house where they can be safely monitored. After awakening his children, Atticus's first directive to Jem is the following:
"Go down and stand in front of the Radley Place. Keep out of the way, do you hear? See which way the wind's blowing? . . . Do as I tell you. Run now. Take care of Scout, you hear? Don't let her out of your sight" (69).
Atticus mentions the wind to Jem because cinders and ash may have been blowing towards their house. If anything hot lands on their house, it could catch fire, too. Miss Maudie's house has not received the help of a fire truck yet, because the truck is being pushed towards her house rather than driven. The truck must have died due to the unusually cold weather they experience that day. If one house is going down without help from a fire truck, then other houses on the block could catch fire as well. Based on the chaos, it is the best decision to get the kids out of the house, safe, and in view until it is all over.
In the middle of the night, Miss Maudie's house catches fire. Three fire trucks are trying to put out the flames, but the cold hinders the firefighters, and one of the hoses bursts. Atticus wakes the two children and makes them wait by the Radley house so they are well out of the way.