Last Update: 9/1/2025 5:20 PM CDT
Surface high pressure in place in the northeastern quadrant of the CONUS, in conjunction with relatively weak flow in a generally northwesterly upper jet has set the stage for another beautiful day throughout the Chicago area. Highs have generally been able to climb into the upper 70's and low 80's throughout the area (cooler near the lake) under sunny skies, with a 10-15 mph ENE wind gusting up to 20 mph.
High pressure will remain in place tonight, leading to a light ~5 mph wind after sunset, creating a moderately strong radiative cooling regime, and sending lows down to the mid 50's to low 60's (warmer near the city). Current dewpoints ranging from the upper 40's to low 50's will likely rise to the mid-upper 50's as vertical mixing shuts off after sunset, which gives a strong signal at patchy fog development in the early morning hours, most pronounced in grassy/highly vegetated areas outside of the metro. Visibility could shrink to around 5 miles in these outlying areas.
Tomorrow's conditions will be very similar to today's, with sunny skies, perhaps a tad warmer with highs in the low 80's areawide with no strong lake breeze, and a calm wind ~5 mph varying in direction. Same story tomorrow night as tonight; mostly clear with lows ranging from the upper 50's inland to low 60's near the lake, light winds, as well as conditional patchy fog in outlying vegetated areas.