A cool Sunday before a significant warmup

Sunday will be the fourth consecutive day with temperatureswell belownormal to begin October. Officially in Chicago, only twice have the first four days of October had high temperatures below60 degrees, 1883 and 2003. Awarmup will beginMonday, when the high temperature reaches the low60s. A more significantwarmup begins Tuesday as the temperature approaches 70. Above-normal temperatures continue fromTuesday into the upcoming weekend. Some lingering showers are possible Sunday morning before an extended dry period arrives. The active tropical season continues. The track of tropical storm Gamma is being closelywatched as the system has the potential to produce heavy rainfall and generate life-threatening flash flooding to portions ofMexico and western Cuba.