Illinois Climate Data
We offer an Illinois Manual J for $79 in 4-6 hours. We can also offer Illinois Manual S $79 and Illinois Manual D $99.
Below is a collection of Illinois Climate Data and outdoor design conditions. We included an Illinois state average of each category at the bottom of the Manual J climate data table. We created this to allow an easy to use free resource for Manual J professionals to use on jobsites, in the field, and while calculating Manual J heat loss and heat gain reports. If you have a custom set of data from Illinois we would consider adding to the Illinois Climate Data table simply email it to plans@manualjs.com
We can also create a Manual J using climate data from the tables below. Email pdf plans, jobsite address, and square footage to plans@manualjs.com and we will get your Illinois Manual J taken care of.
| Illinois | Elevation in Feet | Latitude North Degrees | Heating 99% Outdoor Dry Bulb | Cooling Outdoor Air 1% Dry Bulb | Cooling Outdoor Air Coincident Wet Bulb | Cooling Design Grains 55% Relative Humidity Indoors | Cooling Design Grains 45% Relative Humidity Indoors | Cooling Design Grains 45% Relative Humidity Indoors | Daily Rating | Heating Design Days 65 degrees/Colling Design Days 50 degrees Ratio |
| Aurora Municipal airport | 705 | 42 | 1 | 88 | 74 | 30 | 37 | 44 | M | 2.22 |
| Belleville, Scott Air Force Base | 453 | 38 | 10 | 93 | 77 | 44 | 51 | 58 | M | 1.13 |
| Bloomington (Peoria DD) | 875 | 40 | –2 | 90 | 74 | 31 | 38 | 45 | M | 1.8 |
| Cahokia, airport | 413 | 39 | 14 | 91 | 76 | 43 | 50 | 56 | M | 1.06 |
| Carbondale | 411 | 37 | 7 | 93 | 77 | 44 | 51 | 57 | M | 1.31 |
| Champaign, Urbana | 754 | 40 | 2 | 92 | 74 | 28 | 34 | 41 | M | 1.77 |
| Chicago, Meigs Field | 593 | 41 | 3 | 89 | 73 | 26 | 33 | 40 | M | 1.72 |
| Chicago Midway airport | 617 | 42 | 4 | 90 | 73 | 27 | 34 | 41 | M | 1.77 |
| Chicago Ohare international airport | 673 | 42 | 2 | 89 | 73 | 29 | 36 | 42 | M | 2.08 |
| Chicago CO | 647 | 41 | 2 | 91 | 74 | 29 | 36 | 43 | L | 1.72 |
| Danville | 696 | 40 | 1 | 90 | 74 | 31 | 38 | 44 | M | 1.59 |
| Decatur | 699 | 40 | 5 | 91 | 76 | 41 | 47 | 54 | M | 1.55 |
| Dixon | 785 | 41 | –2 | 90 | 74 | 31 | 38 | 45 | M | 2.56 |
| Elgin | 700 | 42 | –2 | 88 | 74 | 34 | 41 | 48 | M | 2.53 |
| Freeport | 856 | 42 | –4 | 89 | 73 | 27 | 34 | 40 | M | 2.8 |
| Galesburg | 764 | 41 | –2 | 91 | 75 | 36 | 42 | 49 | M | 1.96 |
| Glenview Naval Auxilary Air Station | 653 | 42 | 2 | 90 | 73 | 26 | 32 | 39 | M | 2 |
| Greenville (Vandalia DD) | 541 | 39 | 4 | 92 | 75 | 33 | 40 | 47 | M | 1.49 |
| Joliet | 581 | 41 | 0 | 90 | 74 | 31 | 37 | 44 | M | 2.15 |
| Kankakee | 629 | 41 | 1 | 90 | 74 | 31 | 37 | 44 | M | 2.03 |
| LaSalle, Peru | 654 | 41 | –2 | 91 | 75 | 35 | 42 | 49 | M | 2.1 |
| Lawrenceville-Vincennes international airport | 430 | 39 | 12 | 91 | 76 | 38 | 45 | 52 | M | 1.16 |
| Macomb (Galesburg DD) | 705 | 40 | 0 | 92 | 76 | 40 | 47 | 54 | M | 1.96 |
| Marseilles Island | 738 | 41 | 0 | 89 | 74 | 33 | 39 | 46 | M | 2.04 |
| Matoon Charleston airport | 722 | 39 | 9 | 90 | 76 | 42 | 49 | 55 | M | 1.38 |
| Moline Quad City international airport | 594 | 41 | 0 | 91 | 75 | 36 | 43 | 50 | M | 1.83 |
| Mount Vernon Automated Weather Observation System | 479 | 38 | 11 | 91 | 76 | 42 | 48 | 55 | M | 1.25 |
| Peoria, Greater Peoria airport | 663 | 41 | 2 | 90 | 75 | 39 | 45 | 52 | M | 1.68 |
| Baldwin Field | 768 | 40 | 3 | 90 | 75 | 38 | 45 | 52 | M | 1.54 |
| Rantoul, Chanute Air Force Base | 737 | 40 | 1 | 91 | 74 | 29 | 36 | 43 | M | 1.78 |
| Rockford, Greater Rockford airport | 745 | 42 | -2 | 89 | 74 | 32 | 38 | 45 | M | 2.27 |
| Scott Air Force Base, Bellevill | 443 | 39 | 10 | 93 | 77 | 42 | 49 | 55 | M | 1.11 |
| Southern Illinois airport | 420 | 38 | 16 | 91 | 77 | 47 | 53 | 60 | M | 1.01 |
| Springfield Capital airport | 614 | 40 | 5 | 91 | 76 | 40 | 46 | 53 | M | 1.48 |
| Sterling Rockfalls | 646 | 42 | 0 | 88 | 74 | 32 | 38 | 45 | M | 2.22 |
| University of Illinois | 774 | 40 | 4 | 90 | 75 | 40 | 46 | 53 | M | 1.63 |
| Waukegan | 727 | 42 | –3 | 89 | 74 | 33 | 39 | 46 | M | 2.72 |
| West Chicago, Du Page airport | 758 | 42 | 1 | 88 | 74 | 33 | 40 | 46 | M | 2.25 |
| Illinois State Average | 649 | 40.4210526316 | 4.1935483871 | 90.3157894737 | 74.7368421053 | 34.8157894737 | 41.4210526316 | 48.2105263158 | M | 1.8065789474 |
