Decatur weather in January 2027

Q: How cold is it in Decatur in January?

Daytime temperatures usually reach -1°C in Decatur in January, falling to -10°C at night.

Q: How sunny is it in Decatur in January?

There are normally 4 hours of bright sunshine each day in Decatur in January - that's 45% of daylight hours.

Q: Is the sea cold around Decatur in January?

The average sea temperature around Decatur in January is 4°C.

Q: Does it rain in Decatur in January?

There are usually 12 days with some rain in Decatur in January and the average monthly rainfall is 44mm. Rain may fall as snow in this month.

Expect daytime maximum temperatures of 34°F in Decatur, Illinois in January based on long-term weather averages. There are 5 hours of sunshine per day on average with 10 days with some rainfall and typically 1.9 inches of rainfall in the month, which might fall as snow.

34
34°F max day temperature
5
5 hours of sunshine per day
10
10 days with some rainfall
16
16°F min night temperature
10
10 hours of daylight per day
0
No heat & humidity
1.9
1.9 inches of monthly rainfall
2
2 (Low) UV index

More about Decatur

Decatur by month

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

Recommended for Illinois

Love Holidays sale: up to £600 off holidays

Sale

Save up to £600 on selected holidays in 2026/2027
Book discounted holidays with 'Sale' label
Discounts varies by destination & holiday type. T&Cs apply

Go to Love Holidays deal >>

Expires at 23:59 on Sunday 8th Feb 2026 · View all Love Holidays offers

The January weather guide for Illinois (Decatur) 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) | Imperial (°F)

More about the USA

How cold is it in Decatur in January?

Daytime temperatures usually reach 30°F in Decatur in January, falling to 14°F at night.

How sunny is it in Decatur in January?

There are normally 4 hours of bright sunshine each day in Decatur in January - that's 45% of daylight hours.

How warm is the sea around Decatur in January?

The average sea temperature around Decatur in January is 39°F.

Does it rain in Decatur in January?

There are usually 12 days with some rain in Decatur in January and the average monthly rainfall is 1.7 inches. Rain may fall as snow in this month.