Chicago has experienced measurable rain on about one Halloween in three of the 142 years of rainfall records dating from 1871, and most of those occurrences consisted of rather light rain. Significant rains — at least one-quarter inch — fell on 16 Halloweens, or about one in nine. Unfortunately for ghosts and goblins prowling the area this Halloween, the expectation is that umbrellas and raincoats will be the best attire — an inch or more of rain is likely. Chicago’s run of 13 consecutive days with subnormal temperatures ended on Tuesday and overall readings are forecast to average above normal through the next seven days, despite a brief cool-down on the weekend. With luck, the city will experience four days with afternoon temperatures of 60 degrees or higher in the current seven-day forecast cycle.