Weather in Hamilton in September

Prime time. If you get to pick your dates, September is the one. Highs average 24.9 °C, lows 12.9 °C, and rain falls on 11 days — nothing in the month is working against you.

September is the highest-scoring month of the twelve. The nearest rival is June, and the month at the other end of the year is January.

Rain on 11 days, 2 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

Averages flatten a month, and this one hides a few things: 4 days top 30 °C — hot spells arrive, but they break. Across the twenty years measured, the hottest September day reached 36.6 °C and the coldest night fell to 3.9 °C, and the wettest single day dropped 28 mm — roughly 41% of the month's rain in one day.

September is statistically steady but not small: the year-to-year variation is modest in relative terms, yet the wettest September on record still delivered 113 mm against 37 mm in the driest. In a month this wet, even a tame spread is a lot of rain in absolute terms — the 69 mm average is a reasonable planning figure, not a promise.

Wind is light at 9.2 km/h, so the temperature on the page is close to the temperature on your skin, and humidity is unremarkable at 71%.

How September sits in the year

The month is on the way down: 3.9 °C cooler than August, with October dropping another 8.8 °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 Hamilton's extremes of 15.4 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 — 39 °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 Hamilton versus nearby

If Hamilton is one option among several, the nearby comparison is worth making. Toronto is close enough to be a coin toss — 4.1 °C cooler, 2 days more rain. Buffalo is close enough to be a coin toss — within a degree on temperature, 2 days more rain.

So: September is the answer for Hamilton. If it is booked out or priced out, June is the next best thing at 2 points behind, and January is the month to keep off the shortlist.

Every month in Hamilton

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