Heavy rain and isolated severe thunderstorms may continue to bring flash and urban flooding to the northern Mid-Atlantic and southern New England through tonight. Isolated dry thunderstorms will continue to bring a fire weather threat to the northwestern Great Basin through Friday. Read More >
![]() |
|||
Current Conditions | Forecast Overview | Severe Storms | Hydrology |
NOTE: Reload/refresh this page manually to display the most recent information. |
|
Overview |
|
Location-Specific Hourly Weather Graph |
|
Hazardous Weather Outlook |
|
Technical Forecast Discussion |
869 FXUS63 KLOT 312313 AFDLOT Area Forecast Discussion National Weather Service Chicago/Romeoville, IL 613 PM CDT Thu Jul 31 2025 .KEY MESSAGES... - Wildfire smoke will remain in the area through the weekend. - High waves and rip currents will lead to a high swim risks at all Lake Michigan beaches at least into Friday. - Pleasant conditions will prevail through the weekend with highs in the mid 70s to around 80, and lows in the 60s in Chicago and 50s elsewhere. && .DISCUSSION... Issued at 227 PM CDT Thu Jul 31 2025 Through Friday: CONUS-scale GOES-19 water vapor imagery depicts broad upper- level troughing across eastern Canada and the northern Great Lakes atop an elongated surface high pressure system centered over the Upper Mississippi River Valley. The resulting pattern has allowed for pleasant conditions characterized by relatively low humidity values and seasonably cool temperatures to prevail across the region. The only fly in the ointment on an otherwise comfortable day is hazy skies due to wildfire smoke rounding the southeastern corner of the surface high. Indeed, visibilities across the region have uniformly been between 3 and 5 miles, with several locations dropping to as low as 2 miles from time to time. Tonight, the surface high pressure system in the Upper Mississippi River Valley will shimmy eastward toward Lake Superior. At the same time, a subtle inverted surface trough (currently over central Lower Michigan) will evolve southwestward over Lake Michigan and into northeastern Illinois. The net effect should be a shift in wind direction from northeasterly to easterly. As this occurs, the back edge of the thickest near-surface smoke should shift southwestward away from our area. Meanwhile, increasing convergence along the shoreline of Lake Michigan in tandem with respectable lake instability (marine airmass/850mb temperature differentials pushing 12-14C) should allow for a stratocumulus field to develop and expand westward into northeastern Illinois. In spite of marginal moisture in the convective layer, the degree of shoreline convergence and lake instability suggests scattered sprinkles if not showers may develop overnight, favoring areas north of I-80. So, opted to introduce a 20% chance of showers. Elsewhere, the relatively low humidity levels should lead to another relatively cool night with lows in the upper 50s to around 60. The surface high pressure system will continue to serve as the primary influence to our local weather tomorrow (Friday) as it settles over the central Great Lakes. Forecast soundings depict a pocket of dry air advecting into the region by mid-morning, which should encourage any lingering lake-induced stratocumulus clouds to erode. While near-surface smoke should be southwest of our area tomorrow, upper-level smoke will still stream deregulate overhead leading to a murky appearance to the sky. Highs will hence be similar to today and in the low to mid 70s. Borchardt Friday Night through Thursday: Expansive high pressure will remain centered across Wisconsin and Lower Michigan and bring dry and mostly clear conditions through the weekend. Expect high temps to range from the mid 70s near the lake to around 80 inland. Min temps will be seasonably cool with low/mid 60s in the Chicago urban core and 50s elsewhere. Cannot rule out upper 40s for the typically colder spots of interior northern Illinois Friday night. The surface high will drift eastward to the East Coast early next week as persistent clusters of convection track westward over the southeast and Gulf Coast. Meanwhile, a mid-level trough currently west of the California coast is progged to dislodge a weaker wave across the Rockies and into the central CONUS on Monday before crossing our area on Tuesday. Some of the Atlantic-based moisture will be drawn NNW toward the lower Ohio and mid-Mississippi River Valleys by Monday and especially Tuesday. This would ultimately support isolated to widely scattered diurnally-driven thunderstorms as close as central Illinois Monday afternoon and over the entire forecast area on Tuesday. A low-amplitude ridge nosing northeastward into the southern Great Lakes may then bring drier conditions Wednesday and Thursday next week. Kluber && .AVIATION /00Z TAFS THROUGH 06Z FRIDAY/... Issued at 612 PM CDT Thu Jul 31 2025 The main concerns for the 00Z TAF period include: * MVFR vsbys due to smoke expected to improve this evening Vsbys in the 3 to 5 SM range late this afternoon due to FU are expected to improve to VFR later this evening across all sites. Haze may keep vsbys below 10 SM during the day on Friday, but VFR is anticipated. Meanwhile, NE winds will continue gusting to between 20 and 25 kt through around mid-evening before subsiding to below 10 kt for the overnight. Expect NE winds to 10 to 15 kt during the daytime on Friday going northerly below 10 kt late in the evening. Doom && .LOT WATCHES/WARNINGS/ADVISORIES... IL...Air Quality Alert until midnight CDT Friday night for ILZ003- ILZ004-ILZ005-ILZ006-ILZ008-ILZ010-ILZ011-ILZ012-ILZ013- ILZ019-ILZ020-ILZ021-ILZ023-ILZ032-ILZ033-ILZ039-ILZ103- ILZ104-ILZ105-ILZ106-ILZ107-ILZ108. Beach Hazards Statement through Friday afternoon for ILZ006- ILZ103-ILZ104. IN...Beach Hazards Statement through Friday afternoon for INZ001- INZ002. Air Quality Alert until midnight CDT tonight for INZ001-INZ002- INZ010-INZ011. LM...Small Craft Advisory until 9 AM CDT Friday for the IL and IN nearshore waters. && $$ Visit us at weather.gov/chicago |
Medium-Range Outlooks |
3 to 7 Day National Hazards Outlook | 8 to 14 Day National Hazards Outlook | ||
![]() |
![]() |
||
8 to 14 Day Temperature Outlook | 8 to 14 Day Precipitation Outlook | ||
![]() |
![]() |
Additional Resources |