Weather in Grand Rapids in September

Prime time. September is about as good as Grand Rapids gets. Highs average 23.4 °C, lows 12.2 °C, and rain falls on 10 days — nothing in the month is working against you.

September ranks 2 of 12 in Grand Rapids. Only July scores clearly higher, and the difference is small enough to be settled by price rather than weather.

Rain on 10 days, 3 of them heavy. Enough to need a plan B, not enough to need a plan around it. Nothing specialised needed — this is the month you pack for the trip rather than for the weather.

What the averages hide

The averages here are honest — no hidden extremes worth planning around. Across the twenty years measured, the hottest September day reached 33.4 °C and the coldest night fell to 2.9 °C, and the wettest single day dropped 67 mm — roughly 85% of the month's rain in one day.

September is moderately variable: 12 mm in the driest year against 213 mm in the wettest, around an average of 79 mm. Roughly two Septembers in three land near that average, and the third does something else entirely.

Wind is light at 9.3 km/h, so the temperature on the page is close to the temperature on your skin, and humidity is unremarkable at 74%.

How September sits in the year

The month is on the way down: 3.2 °C cooler than August, with October dropping another 7.9 °C. The first week and the last are not the same trip.

Daylight in September

12.6 hours of daylight, losing 1.4 hours across the month. That is between Grand Rapids's extremes of 15.3 and 9 hours, so days are long enough not to constrain the plan.

An inland climate

With no coast nearby, the year swings a fair way — 35.3 °C between the warmest afternoons and the coldest nights, wider than any coastal city at this latitude would manage.

How busy it gets

Peak season. Expect the highest prices of the year and to be booking well ahead.

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

September in Grand Rapids versus nearby

If Grand Rapids 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, the same number of rain days. Chicago is close enough to be a coin toss — within a degree on temperature, the same number of rain days.

So: September is effectively as good as it gets here — 0 points behind July, which is inside the margin where the weather stops being the deciding factor and price starts being it.

Every month in Grand Rapids

See all twelve months in Grand Rapids, or where else to go in September.