my smoke detectors keep going off.?

About 6 months ago my smoke detectors started chirping, so we went around and changed all the batteries in them. They are also hard wired into my house. Up tell about a week ago occasionally they would just randomly go off for 10-15 seconds for no reason. This whole past week they have been going off 2-6 times a day every day. They also just keep going off until I silence them. Its at all hours of the day and night. My kids have started to just egg nor them, which is very worry some to me just in case there really is a fire they would just think its the smoke detectors going off and not safely get out of the house. The weather has been really nice out for the past two weeks here in Arizona so we have been opening our windows to let in some fresh air. I don't know if this is causing my problems with my smoke detectors or if it's just a coincident. I could use some help so my neighbors will stop thinking that I am a bad cook. lol.