(57.7) (77.9) Daily mean °C −3.3 −4.3 −1.0 4.5 10.1 14.1 17.2 16.0 11.3 6.5 1.3 −1.9 5.9 (°F) (26.1) (24.3) (30.2) (40.1) (50.2) (57.4) (63.0) (60.8) (52.3) (43.7) (34.3) (28.6) (42.6) Average low 15.9 13.2 13.3 13.8 14.9 16.9 18.4 19.4 19.4 18.0 16.1 14.5 15.9 °C (°F) (68) (72) (81) (91) (100) (104) (97) (93) (95) (91) (82) (70) (87) Average low 21 22 23 24 25 26 27 28 29 30 35 37 39 40 41 43 44 45 49 55 57 59 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 □ OR–UT □ PA–MA 85 86 □ ID □ PA–NY 87 □ NC □ NY 89 90 91 92 93 94 95 96 97 98 99 101 163 400 412 425 Mainline highways Divided routes Special routes