Marion weather in August 2026

Q: How hot is it in Marion in August?

Daytime temperatures usually reach 28°C in Marion in August with moderate heat and humidity, falling to 16°C at night.

Q: How sunny is it in Marion in August?

There are normally 9 hours of bright sunshine each day in Marion in August - that's 67% of daylight hours.

Q: How warm is the sea around Marion in August?

The average sea temperature around Marion in August is 21°C.

Q: Does it rain in Marion in August?

There are usually 9 days with some rain in Marion in August and the average monthly rainfall is 97mm.

Expect daytime maximum temperatures of 31°C in Marion, Illinois in August and high heat and humidity based on long-term weather averages. There are 10 hours of sunshine per day on average with typically 88 mm of rainfall in the month.

31
31°C max day temperature
10
10 hours of sunshine per day
8
8 days with some rainfall
18
18°C min night temperature
14
14 hours of daylight per day
H
High heat & humidity
88
88 mm of monthly rainfall
9
9 (Very High) UV index

More about Marion

Marion by month

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Recommended for Illinois

ALL sale: Top winter deals on North America hotels

Sale

Save on hotel stays in North America with Accor
ALL-Accor Live Limitless members get extra 10% off
Travel before 31st May 2026 (inclusive)

Go to ALL deal >>

Expires at 23:59 on Monday 30th Mar 2026 · View all ALL offers

The August weather guide for Illinois (Marion) shows long term weather averages processed from data supplied by CRU (University of East Anglia), the Met Office & the Netherlands Meteorological Institute. Find out more about our data sources.

Metric (°C / mm) | Imperial (°F / inches)