Chicago Weather Forecast: Major Temperature Swing & Thunderstorms—Timing, Maps, and Safety Tips

Chicago is waking up to a soggy Sunday as a fall storm system drenches the metro area and whips up northwest winds near 20 mph. The National Weather Service notes that rain will gradually shift east during the afternoon, giving way to late-day breaks of sun while temperatures struggle in the upper-50s. What to expect over the next 72 hours • Tonight: Showers diminish before midnight; lows slide to the upper-40s, so grab an extra jacket if you’re out late. • Monday: A quick warm-up rides in behind the departing low. Sunshine and a gusty southwest breeze push highs to 63-66 °F—ideal for commuters and anyone catching the Bears game watch parties downtown. • Tuesday: Clouds thicken again as a sharp cold front races south from Wisconsin. Expect afternoon sprinkles and falling temps; daytime highs peak near 56 °F before dropping into the low-40s by evening. Mid-week temperature roller coaster By Wednesday, the new air mass settles over the lakefront, capping highs in the low-50s. Wind chills early Thursday could dip into the upper-30s, a not-so-subtle reminder that winter isn’t far behind. Long-range models hint at another burst of rain next weekend, but the first hard freeze still appears at least 10 days out. Lake Michigan impacts Steady northwest winds today build 4- to 7-foot waves along Chicago’s shoreline. Beachgoers and runners on the Lakefront Trail should expect splash-over and chilly spray. Small-craft operators should remain in port until winds ease Monday afternoon. Commuter & event outlook • CTA & Metra: Wet rails and slick platforms through midday Sunday; minor delays possible. • O’Hare & Midway: Scattered 20- to 30-minute flight delays likely until ceilings lift this evening. • Marathon training runs, pumpkin-patch trips, and Navy Pier events look much brighter Monday with a lighter breeze and dry pavement. Seasonal context Chicago averaged 0.86 in of rain during the first half of October; today’s storm alone could add 0.25–0.50 in across the city, nudging totals closer to the monthly norm of 3.1 in. Meanwhile, the city has yet to record its first 40 °F low—about a week later than the 30-year average—signaling that mild lake temperatures are still moderating overnight chill. Safety tips • Keep storm drains clear of leaves to reduce street flooding. • Secure Halloween decorations; gusts to 35 mph can topple lightweight inflatables. • Dress in layers Monday: the morning bus stop feels crisp, but the lunch hour turns almost spring-like. Stay tuned to live radar updates, push alerts, and daily Chicago weather headlines here as we track every temperature swing and raindrop this October.