<Tr> <Th> Percent possible sunshine </Th> <Td> 46 </Td> <Td> 46 </Td> <Td> 51 </Td> <Td> 54 </Td> <Td> 62 </Td> <Td> 68 </Td> <Td> 69 </Td> <Td> 66 </Td> <Td> 60 </Td> <Td> 56 </Td> <Td> 38 </Td> <Td> 37 </Td> <Td> 56 </Td> </Tr> <Tr> <Td_colspan="14"> Source: NOAA (relative humidity and sun 1961--1990) </Td> </Tr> <Table> <Tr> <Th_colspan="14"> (hide) Climate data for Chicago Aurora Municipal Airport, Illinois 1981--2010 normals </Th> </Tr> <Tr> <Th> Month </Th> <Th> Jan </Th> <Th> Feb </Th> <Th> Mar </Th> <Th> Apr </Th> <Th> May </Th> <Th> Jun </Th> <Th> Jul </Th> <Th> Aug </Th> <Th> Sep </Th> <Th> Oct </Th> <Th> Nov </Th> <Th> Dec </Th> <Th> Year </Th> </Tr> <Tr> <Th> Record high ° F (° C) </Th> <Td> 67 (19) </Td> <Td> 72 (22) </Td> <Td> 83 (28) </Td> <Td> 93 (34) </Td> <Td> 105 (41) </Td> <Td> 106 (41) </Td> <Td> 111 (44) </Td> <Td> 105 (41) </Td> <Td> 103 (39) </Td> <Td> 90 (32) </Td> <Td> 81 (27) </Td> <Td> 69 (21) </Td> <Td> 111 (44) </Td> </Tr> <Tr> <Th> Average high ° F (° C) </Th> <Td> 29.1 (− 1.6) </Td> <Td> 33.7 (0.9) </Td> <Td> 47.0 (8.3) </Td> <Td> 60.0 (15.6) </Td> <Td> 70.6 (21.4) </Td> <Td> 80.1 (26.7) </Td> <Td> 83.5 (28.6) </Td> <Td> 81.2 (27.3) </Td> <Td> 74.9 (23.8) </Td> <Td> 62.2 (16.8) </Td> <Td> 47.8 (8.8) </Td> <Td> 32.8 (0.4) </Td> <Td> 58.6 (14.8) </Td> </Tr> <Tr> <Th> Daily mean ° F (° C) </Th> <Td> 20.8 (− 6.2) </Td> <Td> 24.9 (− 3.9) </Td> <Td> 37.0 (2.8) </Td> <Td> 48.5 (9.2) </Td> <Td> 58.8 (14.9) </Td> <Td> 68.8 (20.4) </Td> <Td> 71.7 (22.1) </Td> <Td> 70.1 (21.2) </Td> <Td> 62.8 (17.1) </Td> <Td> 50.6 (10.3) </Td> <Td> 38.1 (3.4) </Td> <Td> 25.1 (− 3.8) </Td> <Td> 48.1 (9) </Td> </Tr> <Tr> <Th> Average low ° F (° C) </Th> <Td> 12.6 (− 10.8) </Td> <Td> 16.2 (− 8.8) </Td> <Td> 26.9 (− 2.8) </Td> <Td> 37.0 (2.8) </Td> <Td> 47.1 (8.4) </Td> <Td> 57.5 (14.2) </Td> <Td> 59.8 (15.4) </Td> <Td> 59.0 (15) </Td> <Td> 50.7 (10.4) </Td> <Td> 39.0 (3.9) </Td> <Td> 28.4 (− 2) </Td> <Td> 17.5 (− 8.1) </Td> <Td> 37.6 (3.1) </Td> </Tr> <Tr> <Th> Record low ° F (° C) </Th> <Td> − 33 (− 36) </Td> <Td> − 25 (− 32) </Td> <Td> − 15 (− 26) </Td> <Td> 8 (− 13) </Td> <Td> 21 (− 6) </Td> <Td> 34 (1) </Td> <Td> 40 (4) </Td> <Td> 37 (3) </Td> <Td> 25 (− 4) </Td> <Td> 11 (− 12) </Td> <Td> − 11 (− 24) </Td> <Td> − 25 (− 32) </Td> <Td> − 33 (− 36) </Td> </Tr> <Tr> <Th> Average precipitation inches (mm) </Th> <Td> 1.47 (37.3) </Td> <Td> 1.62 (41.1) </Td> <Td> 2.23 (56.6) </Td> <Td> 3.38 (85.9) </Td> <Td> 4.26 (108.2) </Td> <Td> 4.01 (101.9) </Td> <Td> 4.19 (106.4) </Td> <Td> 4.12 (104.6) </Td> <Td> 3.44 (87.4) </Td> <Td> 3.12 (79.2) </Td> <Td> 3.14 (79.8) </Td> <Td> 1.96 (49.8) </Td> <Td> 36.86 (936.2) </Td> </Tr> <Tr> <Th> Average snowfall inches (cm) </Th> <Td> 100 (254) </Td> <Td> 70 (178) </Td> <Td> 37 (94) </Td> <Td> 8 (20) </Td> <Td> 0 (0) </Td> <Td> 0 (0) </Td> <Td> 0 (0) </Td> <Td> 0 (0) </Td> <Td> 0 (0) </Td> <Td> (3) </Td> <Td> 14 (36) </Td> <Td> 75 (191) </Td> <Td> 305 (775) </Td> </Tr> <Tr> <Th> Average precipitation days (≥ 0.01 in) </Th> <Td> 9.7 </Td> <Td> 7.8 </Td> <Td> 10.4 </Td> <Td> 11.8 </Td> <Td> 11.2 </Td> <Td> 10.2 </Td> <Td> 9.3 </Td> <Td> 10.0 </Td> <Td> 8.9 </Td> <Td> 8.9 </Td> <Td> 10.2 </Td> <Td> 10.7 </Td> <Td> 119.1 </Td> </Tr> <Tr> <Th> Average snowy days (≥ 0.1 in) </Th> <Td> 6.7 </Td> <Td> 4.5 </Td> <Td> 2.1 </Td> <Td> 0.4 </Td> <Td> 0 </Td> <Td> 0 </Td> <Td> 0 </Td> <Td> 0 </Td> <Td> 0 </Td> <Td> 0.1 </Td> <Td> 1.2 </Td> <Td> 4.9 </Td> <Td> 19.9 </Td> </Tr> <Tr> <Td_colspan="14"> Source: NOAA (normals, 1981--2010) </Td> </Tr> </Table> <Tr> <Th_colspan="14"> (hide) Climate data for Chicago Aurora Municipal Airport, Illinois 1981--2010 normals </Th> </Tr>

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