Illinois frost dates: N
| City | Last frost | First frost | Season | Zone |
|---|---|---|---|---|
| Nachusa | Apr 21 | Oct 19 | 181 d | 5b |
| Naperville | Apr 28 | Oct 16 | 171 d | 5b |
| Nashville | Apr 7 | Oct 26 | 202 d | 6b |
| Nason | Apr 4 | Oct 27 | 206 d | 6b |
| National Stock Yards | Apr 8 | Oct 26 | 201 d | 7a |
| Nauvoo | Apr 12 | Oct 25 | 196 d | 6a |
| Nebo | Apr 4 | Nov 1 | 211 d | 6a |
| Neoga | Apr 16 | Oct 20 | 187 d | 6b |
| Neponset | Apr 24 | Oct 17 | 176 d | 5b |
| New Athens | Apr 12 | Oct 20 | 191 d | 7a |
| New Baden | Apr 12 | Oct 20 | 191 d | 6b |
| New Bedford | Apr 24 | Oct 14 | 173 d | 5b |
| New Berlin | Apr 15 | Oct 22 | 190 d | 6a |
| New Boston | Apr 14 | Oct 24 | 193 d | 5b |
| New Burnside | Apr 14 | Oct 21 | 190 d | 7a |
| New Canton | Apr 4 | Nov 4 | 214 d | 6b |
| New Douglas | Apr 13 | Oct 24 | 194 d | 6b |
| New Haven | Apr 5 | Oct 31 | 209 d | 7a |
| New Holland | Apr 17 | Oct 18 | 184 d | 6a |
| New Lenox | Apr 19 | Oct 25 | 189 d | 6a |
| New Memphis | Apr 12 | Oct 20 | 191 d | 6b |
| New Salem | Apr 14 | Oct 21 | 190 d | 6a |
| New Windsor | Apr 22 | Oct 19 | 180 d | 5b |
| Newark | Apr 20 | Oct 23 | 186 d | 5b |
| Newman | Apr 15 | Oct 20 | 188 d | 6a |
| Newton | Apr 13 | Oct 22 | 192 d | 6b |
| Niantic | Apr 14 | Oct 24 | 193 d | 6a |
| Niles | Apr 16 | Oct 28 | 195 d | 6a |
| Nilwood | Apr 7 | Oct 29 | 205 d | 6b |
| Niota | Apr 12 | Oct 25 | 196 d | 6a |
| Noble | Apr 15 | Oct 23 | 191 d | 6b |
| Nokomis | Apr 17 | Oct 23 | 189 d | 6a |
| Nora | Apr 27 | Oct 9 | 165 d | 5a |
| Normal | Apr 25 | Oct 16 | 174 d | 6a |
| Norris | Apr 16 | Oct 23 | 190 d | 5b |
| Norris City | Apr 15 | Oct 19 | 187 d | 7a |
| North Aurora | Apr 19 | Oct 23 | 187 d | 5b |
| North Chicago | Apr 30 | Oct 21 | 174 d | 6a |
| North Henderson | Apr 20 | Oct 19 | 182 d | 5b |
| Northbrook | Apr 26 | Oct 21 | 178 d | 6a |