Weather in Chicago in May

Shoulder season. May sits in between. You will get good days and you will lose some. Highs sit at 15 °C and the day is short; this is an indoors-with-excursions month, not an outdoors-all-day one.

May ranks 6 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 13 days, 4 of them heavy. Enough to need a plan B, not enough to need a plan around it. Layers, and a genuinely waterproof outer — at 15 °C the difference between a good day and a miserable one is entirely down to what you are wearing.

What the averages hide

The averages here are honest — no hidden extremes worth planning around. Across the twenty years measured, the hottest May day reached 29 °C and the coldest night fell to 0.8 °C, and the wettest single day dropped 72 mm — roughly 62% of the month's rain in one day.

May is statistically steady but not small: the year-to-year variation is modest in relative terms, yet the wettest May on record still delivered 197 mm against 42 mm in the driest. In a month this wet, even a tame spread is a lot of rain in absolute terms — the 117 mm average is a reasonable planning figure, not a promise.

Wind is light at 12.9 km/h, so the temperature on the page is close to the temperature on your skin, and humidity runs at 83%, high enough to notice on the warm days without dominating them.

How May sits in the year

The month is on the way up: 4.8 °C warmer than April, and June adds another 6.1 °C. Late in the month feels noticeably different from the start of it, which is worth knowing if the trip is short.

Daylight in May

14.5 hours of daylight, gaining 1 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.

May in Chicago versus nearby

If Chicago is one option among several, the nearby comparison is worth making. Milwaukee is a better bet in May — 3.9 °C warmer, 1 day more rain. Grand Rapids is a better bet in May — 4.5 °C warmer, the same number of rain days.

So: May is a compromise. September is 23 points better and is what Chicago is actually like at its best — worth moving the trip for if that is possible, and worth adjusting expectations for if it is not.

Every month in Chicago

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