Weather in Knoxville in September

A good month. September is a solid month to be in Knoxville. Highs average 29.3 °C, lows 16.6 °C, and rain falls on 10 days — nothing in the month is working against you.

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

Rain on 10 days, 3 of them heavy. Enough to need a plan B, not enough to need a plan around it. Pack for 29.3 °C days and 16.6 °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: 13 days top 30 °C — hot spells arrive, but they break. Across the twenty years measured, the hottest September day reached 38.4 °C and the coldest night fell to 5.1 °C, and the wettest single day dropped 95 mm — roughly 97% of the month's rain in one day.

September is moderately variable: 8 mm in the driest year against 167 mm in the wettest, around an average of 98 mm. Roughly two Septembers in three land near that average, and the third does something else entirely.

Wind is light at 2.6 km/h, so the temperature on the page is close to the temperature on your skin, and humidity is unremarkable at 69%.

How September sits in the year

The month is on the way down: 2.6 °C cooler than August, with October dropping another 6.3 °C. The first week and the last are not the same trip. Rain has already shifted: 5 days fewer than August had.

Daylight in September

12.5 hours of daylight, losing 1.1 hours across the month. That is between Knoxville's extremes of 14.6 and 9.7 hours, so days are long enough not to constrain the plan.

An inland climate

With no coast nearby, the year swings a fair way — 33.1 °C between the warmest afternoons and the coldest nights, wider than any coastal city at this latitude would manage.

How busy it gets

Busy. Popular without being frantic; book the things you care about, improvise the rest.

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

September in Knoxville versus nearby

If Knoxville is one option among several, the nearby comparison is worth making. Atlanta is close enough to be a coin toss — within a degree on temperature, 1 day less rain. Nashville is close enough to be a coin toss — within a degree on temperature, 1 day less rain.

So: September works, with October the better month by 12 points if the dates can move. If they cannot, nothing here should stop you booking.

Every month in Knoxville

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