Weather in Chicago in October

Shoulder season. October sits in between. You will get good days and you will lose some. Highs average 15.2 °C, lows 9.7 °C, and rain falls on 11 days — nothing in the month is working against you.

October ranks 5 of 12 in Chicago: past the worst of the year but short of September, which is the month to book if the dates are open.

Rain on 11 days, 3 of them heavy. Enough to need a plan B, not enough to need a plan around it. Pack for 15.2 °C days and 9.7 °C nights; the spread matters more here than any single number.

What the averages hide

Averages flatten a month, and this one hides a few things: the day barely swings — 5.5 °C between the overnight low and the afternoon high. Across the twenty years measured, the hottest October day reached 26.2 °C and the coldest night fell to 0.1 °C, and the wettest single day dropped 57 mm — roughly 58% of the month's rain in one day.

October is moderately variable: 33 mm in the driest year against 221 mm in the wettest, around an average of 99 mm. Roughly two Octobers in three land near that average, and the third does something else entirely.

Wind sits around 17.7 km/h — a steady breeze rather than a nuisance, and welcome on the warmer days, and humidity runs at 77%, high enough to notice on the warm days without dominating them.

How October sits in the year

The month is on the way down: 6.7 °C cooler than September, with November dropping another 6.6 °C. The first week and the last are not the same trip.

Daylight in October

11.2 hours of daylight, losing 1.4 hours across the month. That is between Chicago's extremes of 15.2 and 9.2 hours, so days are long enough not to constrain the plan.

An inland climate

With no coast nearby, the year swings a fair way — 30.2 °C between the warmest afternoons and the coldest nights, wider than any coastal city at this latitude would manage.

How busy it gets

Shoulder. The value months — prices ease off and you get the place closer to itself.

Crowd levels are estimated from climate desirability and school-holiday calendars, not from visitor numbers.

October in Chicago versus nearby

If Chicago is one option among several, the nearby comparison is worth making. Milwaukee is close enough to be a coin toss — within a degree on temperature, 1 day less rain. Grand Rapids is close enough to be a coin toss — within a degree on temperature, 2 days more rain.

So: October works, with September the better month by 18 points if the dates can move. If they cannot, nothing here should stop you booking.

Every month in Chicago

See all twelve months in Chicago, or where else to go in October.