Decatur weather by month

Check out Decatur weather averages by month. Compare detailed monthly climate statistics including temperature, rainfall and sunshine figures.

Temperature
Rainfall
Sunshine & UV index

Temperature in Decatur (°F)

	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Max temperature (daytime)	34	39	52	64	75	84	88	84	79	68	52	37
Min temperature (night-time)	16	19	30	41	52	61	64	63	55	43	34	21
Heat & Humidity	0	0	0	0	0	M	H	M	L	0	0	0

Note: 0 = None, L = Low, M = Moderate, H = High, VH = Very high, E = Extreme

Sunshine & UV index in Decatur

	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Daily hours of sunshine	5	5	6	8	9	10	10	9	8	7	4	4
Daily hours of daylight	10	11	12	13	14	15	15	14	12	11	10	9
UV Index (Maximum)	2	3	4	6	8	9	9	8	6	4	2	2

Rainfall in Decatur

	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Number of days with some rain	10	9	12	12	10	9	9	8	8	8	10	11
Average monthly rainfall (inches)	1.9	1.9	3.1	3.8	4.0	3.9	4.2	3.7	3.2	2.8	3.0	2.8

More about Decatur

Decatur by month

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

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The climate guide for Illinois (Decatur) shows long term monthly 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.

What's the climate like in Decatur?

Decatur has a cold climate with hot summers and some rainfall in all months.

Decatur weather in January

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

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Decatur weather in February

Expect daytime maximum temperatures of 39°F in Decatur, Illinois in February based on long-term weather averages. There are 5 hours of sunshine per day on average with typically 1.9 inches of rainfall in the month, which might fall as snow.

39
39°F max day temperature
5
5 hours of sunshine per day
9
9 days with some rainfall
19
19°F min night temperature
11
11 hours of daylight per day
0
No heat & humidity
1.9
1.9 inches of monthly rainfall
3
3 (Moderate) UV index

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Decatur weather in March

Expect daytime maximum temperatures of 52°F in Decatur, Illinois in March based on long-term weather averages. There are 6 hours of sunshine per day on average with 12 days with some rainfall and typically 3.1 inches of rainfall in the month.

52
52°F max day temperature
6
6 hours of sunshine per day
12
12 days with some rainfall
30
30°F min night temperature
12
12 hours of daylight per day
0
No heat & humidity
3.1
3.1 inches of monthly rainfall
4
4 (Moderate) UV index

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Decatur weather in April

Expect daytime maximum temperatures of 64°F in Decatur, Illinois in April based on long-term weather averages. There are 8 hours of sunshine per day on average with 12 days with some rainfall and typically 3.8 inches of rainfall in the month.

64
64°F max day temperature
8
8 hours of sunshine per day
12
12 days with some rainfall
41
41°F min night temperature
13
13 hours of daylight per day
0
No heat & humidity
3.8
3.8 inches of monthly rainfall
6
6 (High) UV index

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Decatur weather in May

Expect daytime maximum temperatures of 75°F in Decatur, Illinois in May based on long-term weather averages. There are 9 hours of sunshine per day on average with 10 days with some rainfall and typically 4.0 inches of rainfall in the month.

75
75°F max day temperature
9
9 hours of sunshine per day
10
10 days with some rainfall
52
52°F min night temperature
14
14 hours of daylight per day
0
No heat & humidity
4.0
4.0 inches of monthly rainfall
8
8 (Very High) UV index

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Decatur weather in June

Expect daytime maximum temperatures of 84°F in Decatur, Illinois in June based on long-term weather averages. There are 10 hours of sunshine per day on average with typically 3.9 inches of rainfall in the month.

84
84°F max day temperature
10
10 hours of sunshine per day
9
9 days with some rainfall
61
61°F min night temperature
15
15 hours of daylight per day
M
Moderate heat & humidity
3.9
3.9 inches of monthly rainfall
9
9 (Very High) UV index

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Decatur weather in July

Expect daytime maximum temperatures of 88°F in Decatur, Illinois in July and high heat and humidity based on long-term weather averages. There are 10 hours of sunshine per day on average with typically 4.2 inches of rainfall in the month.

88
88°F max day temperature
10
10 hours of sunshine per day
9
9 days with some rainfall
64
64°F min night temperature
15
15 hours of daylight per day
H
High heat & humidity
4.2
4.2 inches of monthly rainfall
9
9 (Very High) UV index

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Decatur weather in August

Expect daytime maximum temperatures of 84°F in Decatur, Illinois in August based on long-term weather averages. There are 9 hours of sunshine per day on average with typically 3.7 inches of rainfall in the month.

84
84°F max day temperature
9
9 hours of sunshine per day
8
8 days with some rainfall
63
63°F min night temperature
14
14 hours of daylight per day
M
Moderate heat & humidity
3.7
3.7 inches of monthly rainfall
8
8 (Very High) UV index

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Decatur weather in September

Expect daytime maximum temperatures of 79°F in Decatur, Illinois in September based on long-term weather averages. There are 8 hours of sunshine per day on average with typically 3.2 inches of rainfall in the month.

79
79°F max day temperature
8
8 hours of sunshine per day
8
8 days with some rainfall
55
55°F min night temperature
12
12 hours of daylight per day
L
Low heat & humidity
3.2
3.2 inches of monthly rainfall
6
6 (High) UV index

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Decatur weather in October

Expect daytime maximum temperatures of 68°F in Decatur, Illinois in October based on long-term weather averages. There are 7 hours of sunshine per day on average with typically 2.8 inches of rainfall in the month.

68
68°F max day temperature
7
7 hours of sunshine per day
8
8 days with some rainfall
43
43°F min night temperature
11
11 hours of daylight per day
0
No heat & humidity
2.8
2.8 inches of monthly rainfall
4
4 (Moderate) UV index

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Decatur weather in November

Expect daytime maximum temperatures of 52°F in Decatur, Illinois in November based on long-term weather averages. There are 4 hours of sunshine per day on average with 10 days with some rainfall and typically 3.0 inches of rainfall in the month.

52
52°F max day temperature
4
4 hours of sunshine per day
10
10 days with some rainfall
34
34°F min night temperature
10
10 hours of daylight per day
0
No heat & humidity
3.0
3.0 inches of monthly rainfall
2
2 (Low) UV index

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Decatur weather in December

Expect daytime maximum temperatures of 37°F in Decatur, Illinois in December based on long-term weather averages. There are 4 hours of sunshine per day on average with 11 days with some rainfall and typically 2.8 inches of rainfall in the month, which might fall as snow.