Decatur (IL) monthly weather averages

Contents

Average daytime temperature

The bar chart below shows the average monthly peak daytime temperatures at Decatur

Decatur average temperature chart (Celsius) Decatur average temperature chart (Fahrenheit)
Average monthly temperatures in Decatur (degrees centigrade and fahrenheit)
  Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
°C 0.4 3.3 10.3 17.9 23.9 28.8 30.5 29.2 26 19.2 11 3.1
°F 32.8 37.9 50.6 64.2 75 83.8 86.9 84.6 78.8 66.6 51.7 37.6

Please note: these are the average peak daytime temperatures (usually around mid-afternoon) so do not show daytime / night highs and lows. To see the daily range of temperatures have a look at the temperature max / min chart below.

Average rainfall & rainy days

The graph below shows the average rainfall and number of rainy days per month.

Decatur monthly rainfall chart (mm) Decatur monthly rainfall chart (inches)
Average monthly rainfall in Decatur (mm and inches)
  Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
mm 49 48 80 96 102 100 107 93 81 71 77 72
inches 1.9 1.9 3.2 3.8 4 3.9 4.2 3.7 3.2 2.8 3 2.8
Rainy days 10 9 12 12 10 9 9 8 9 8 10 11

Average annual rainfall in Decatur: 928mm (365.4 inches)

Average daily sunshine

The bar chart below shows the average daily sunshine hours in Decatur

Decatur average daily sunshine chart
Average daily sunshine Decatur
  Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Hrs sunshine 5.4 5.9 6.5 8 9.6 11 10.9 10 8.7 7.4 4.9 4.4

Day / night temperatures

The graph below shows the daily range of temperatures for each month.

Decatur average minimum / maximum temperatures (Celsius) Decatur average minimum / maximum temperatures (Fahrenheit)
Maximum and minimum daily temperatures in Decatur (degrees centigrade and fahrenheit)
  Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Min °C -9.1 -6.7 -0.6 5.4 10.8 15.7 18 16.7 12.7 6.5 0.8 -5.8
Max °C 0.7 3.5 10.6 18.2 24.2 29.1 30.8 29.5 26.3 19.6 11.2 3.4
Min °F 15.7 19.9 30.9 41.7 51.4 60.3 64.4 62.1 54.9 43.6 33.4 21.7
Max °F 24.4 29.1 41 53.2 63.5 72.3 75.9 73.6 67.1 55.4 42.8 29.8

Sea temperature

The graph below shows the average sea temperature.

Decatur average sea temperature chart (Celsius) Decatur average sea temperature chart (Fahrenheit)
Average sea temperature around Decatur in degrees centigrade and fahrenheit
  Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
°C 8.6 8 8.3 9.5 11.8 15.3 19.6 22.4 20.8 16.2 12.6 10.1
°F 47.5 46.4 46.9 49.1 53.2 59.6 67.2 72.3 69.4 61.2 54.6 50.2

Wind speed

The graph below shows the average wind speed.

Decatur average winspeed by month (km/h) Decatur average winspeed by month (mph)
Average wind speed in Decatur (mph and kmh)
  Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
km/h 19 19 21 20 17 16 13 13 14 16 18 19
mph 12 12 13 13 11 10 8 8 9 10 11 12

A monthly average windspeed of over 16km/h or 10mph suggests a location is fairly windy.

Relative humidity

The graph below shows the average relative humidity.

Decatur relative humidity averages
Average relative humidity in Decatur
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
74% 74% 71% 65% 66% 67% 71% 74% 72% 69% 74% 78%

Other monthly averages

UV index Best time to go?

Beta

Current (hourly) weather 15 day forecast

Decatur weather stats

Decatur weather statistics
Hottest month: July 30.5°C 86.9°F
Driest month: February 48mm 1.9ins
Sunniest month: July 10.9hrs
Coldest month: January 0.4°C 32.7°F
Wettest month: July 107mm 4.2ins
Warmest sea: August 22.4°C 72.3°F
Map showing location of Decatur (39.84031, -88.9548) Decatur map pin © Google

Locations nearby

Top United States locations