Sunday will be the fourth consecutive day with temperatures well below normal to begin October. Officially in Chicago, only twice have the first four days of October had high temperatures below 60 degrees, 1883 and 2003. A warmup will begin Monday, when the high temperature reaches the low 60s. A more significant warmup begins Tuesday as the temperature approaches 70. Above-normal temperatures continue from Tuesday 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 closely watched as the system has the potential to produce heavy rainfall and generate life-threatening flash flooding to portions of Mexico and western Cuba.