Chicago weather in August

August in Chicago: hot, a little rain — an excellent time to visit.

Updated September 2026 · climate normals from ERA5 reanalysis

Chicago🇺🇸 United States · Great Lakes & Midwest · City81
  1. 40Jan
  2. 49Feb
  3. 64Mar
  4. 71Apr
  5. 83May
  6. 86Jun
  7. 76Jul
  8. 81Aug
  9. 91Sep
  10. 73Oct
  11. 62Nov
  12. 46Dec

#4 of 12 months in Chicago · #625 of 1413 destinations to visit in August · comfort 81/100 (tier A)

Days
28°C
Nights
20°C
Wet days
8
Sun
11.4 h
Humidity
74%
Daylight
14 h
Chicago, United States
Photo: Pawel aparatem_go · Pexels

Traveller notes on Chicago in August

Regulars call this month genuinely a coin flip year to year - hot, muggy dog days are common through the first three weeks, but whether a given trip lands in that stretch or gets decent, more comfortable summer weather instead is real luck of the draw. Our row backs the warm, humid average across that range, 27.7C reading as a hot 31C at 74 percent humidity, over 19.6C nights, with 77.7mm of rain across 8.2 days. Regulars recommend keeping the more strenuous plans to morning or late afternoon, since midday in a hot stretch is genuinely draining. The beaches and lake are called a real highlight this month regardless, warm enough for a full day by the water. The record: 11.4 hours of sun, a 16.8 kph wind and AQI 56.
CompletelyUnpredictableLuckOfTheDraw · August · 1 month ago · Read more on Tripadvisor ↗

Other months in Chicago

May here can be in the fifties or the eighties and regulars will not choose for you - the instruction is to check the forecast the day you pack and bring layers that fit under a windbreaker. The mechanism they name is the lake: the water is still in the forties Fahrenheit this month, so an east wind makes the shore genuinely cold while the city behind it is pleasant. Our row averages 19.9C reading as 19C over 10.4C nights that feel like 7C, with a 20.7 kph wind and 109.3mm of rain across 10.8 days - a wetter month than its reputation. An evening boat trip wants a sweater whatever the afternoon did. The record: humidity 75 percent, 10.4 hours of sun and AQI 55.
TheLakeIsStillInTheForties · May · 1 month ago · Read more on Tripadvisor ↗
Regulars call June lovely and then explain the catch, which is a single number our row cannot hold: when the wind comes off the lake, downtown runs about ten degrees Fahrenheit under the airport figure the forecast quotes. So the sweater goes in the bag whatever the app says - the same warning the Milwaukee board gives about its own lakefront, eighty miles north. Our averages are 26.5C reading as 28C over 16.7C nights, with a 19.2 kph wind and 93.5mm across 8.6 days. The other cost of June here is company: it is high season for visitors and conventions both. Daylight runs 15.2 hours with 11.9 of sun. The record: humidity 73 percent and AQI 68.
TenDegreesCoolerByTheWater · June · 1 month ago · Read more on Tripadvisor ↗
Chicago-forum threads rate September as close to the best weather-wise month on the calendar: early September still feels like summer, tourist crowds are way down from the July peak, and posters point to a quieter Navy Pier and easier reservations as the payoff. The one caveat several repeat: early September runs noticeably warmer than the tail of the month, so the 'ideal' window narrows the later you book. The record: 25C days, 16.5C nights, 63mm of rain across 6.8 days, 9.6 hours of sun and a clean AQI of 45 - warm, dry enough, and past the humidity that makes Chicago's July a different city.
NavyPierSeptember · September · 1 month ago · Read more on Tripadvisor ↗
Chicago forum threads describe February as slightly less brutal than January but still reliably below-freezing on most days, with real wind chill making temperatures feel meaningfully colder than the thermometer reading - especially near the lake. Interestingly, posters pointed out Chicago's 'Windy City' nickname isn't actually about literal average wind speed, which isn't dramatically higher here than other US cities - it's the wind chill effect combined with the nickname's political-origin history that gets misunderstood. Experiences varied widely across threads, from a visitor comfortably playing tennis outdoors in just a light sweater to another who barely left the hotel - the consistent advice was to prepare for cold and wind but not necessarily expect the worst-case scenario.
LakeMichiganWindyCityRegular · February · 1 month ago · Read more on Tripadvisor ↗

Year-round notes are on Chicago's overview. Add your own note from Chicago's card on the map.

Chicago climate normals — August

Daytime high28°C / 82°F🥵 hot
Nighttime low20°C / 67°F
Feels like (high)31°C / 88°F
Rainfall78 mm / 3.1 in🌦 some rain
Rainy days8 days
Humidity74%💧 humid
Dew point17°C / 62°F
Sunshine11.4 h/day
Daylight13.8 h
Wind17 km/h / 10 mph
Air quality (US AQI)56🙂 moderate

Monthly averages from ERA5 reanalysis. AQI is the mean US Air Quality Index for the month.

Crowds in Chicago in August

How busy the place itself is — school and mass holidays, the months an editor tagged, and how sought-after the weather makes them. Never part of the comfort score.

Peak crowdsLollapalooza, Air and Water Show, Summer break in United States(estimated)

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Peak crowdsBusyShoulder seasonQuiet

Best months for Chicago's weather

Ranked by this destination's own climate comfort score across the year — a different thing from how busy it gets (see Crowds above).

Fair weatherChicago's best weather comes in May, June and September — separate windows, not one continuous season.

JFMAMJJASOND

Best weatherFair weatherToughest weather

What's on in Chicago in August

Recurring seasonal events, natural spectacles, closures and holidays — curated and sourced.

  • Opening

    Lakefront beach season

    22 May – 7 Sep · usuallySummer season opens

    The city's twenty-odd beaches are guarded from Memorial Day weekend to Labor Day and effectively shut either side of it. Lake Michigan takes until August to become anything like swimmable. Source ↗

  • Festival

    Lollapalooza

    28 Jul – 4 Aug · usuallyMusic festivalCrowdedBook early

    Four days and a hundred thousand people a day in Grant Park at the turn of July into August. The Loop hotels reprice around it and Michigan Avenue is a slow walk each evening. Source ↗

  • Festival

    Air and Water Show

    14–18 Aug · usuallyMajor festivalCrowded

    A free two-day show over North Avenue Beach in mid-August, with a full rehearsal on the Friday that most locals prefer. The whole north lakefront is the grandstand. Source ↗

What's on around the world in August →

Nearby, and something's on

Within 300 km of Chicago — a day trip or a short hop — with something on this month. Never part of the comfort score.

Where is Chicago?

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Chicago in August — FAQ

Is August a good time to visit Chicago?
August in Chicago: hot, a little rain — an excellent time to visit. It ranks #4 of 12 months for Chicago on SeasonMap's comfort score (81/100).
What is the weather like in Chicago in August?
In August, Chicago averages a daily high of 27.7°C and a low of 19.6°C, with about 77.7 mm of rain over roughly 8.2 rainy days.
What is the air quality in Chicago in August?
Chicago has a mean US Air Quality Index of about 56 in August.

Within 300 km: Milwaukee's Wisconsin State Fair on 6–16 Aug, and Indianapolis' Brickyard 400 around 15 Jul – 5 Aug.