Illinois frost dates: P
| City | Last frost | First frost | Season | Zone |
|---|---|---|---|---|
| Palatine | Apr 19 | Oct 26 | 190 d | 5b |
| Palestine | Apr 12 | Oct 22 | 193 d | 6b |
| Palmer | Apr 12 | Oct 20 | 191 d | 6a |
| Palmyra | Apr 14 | Oct 21 | 190 d | 6b |
| Paloma | Apr 14 | Oct 23 | 192 d | 6a |
| Palos Heights | Apr 10 | Nov 1 | 205 d | 6a |
| Palos Hills | Apr 19 | Oct 22 | 186 d | 6a |
| Palos Park | Apr 19 | Oct 22 | 186 d | 6a |
| Pana | Apr 17 | Oct 23 | 189 d | 6b |
| Panama | Apr 13 | Oct 24 | 194 d | 6b |
| Papineau | Apr 24 | Oct 16 | 175 d | 5b |
| Paris | Apr 21 | Oct 20 | 182 d | 6a |
| Park Forest | Apr 23 | Oct 20 | 180 d | 6a |
| Park Ridge | Apr 16 | Oct 28 | 195 d | 6a |
| Parkersburg | Apr 15 | Oct 23 | 191 d | 6b |
| Patoka | Apr 9 | Oct 26 | 200 d | 6b |
| Patterson | Apr 13 | Oct 22 | 192 d | 6a |
| Paw Paw | Apr 27 | Oct 15 | 171 d | 5b |
| Pawnee | Apr 7 | Oct 29 | 205 d | 6a |
| Paxton | Apr 23 | Oct 12 | 172 d | 6a |
| Payson | Apr 10 | Oct 27 | 200 d | 6a |
| Pearl | Apr 13 | Oct 22 | 192 d | 6a |
| Pearl City | Apr 26 | Oct 13 | 170 d | 5a |
| Pecatonica | Apr 26 | Oct 13 | 170 d | 5b |
| Pekin | Apr 16 | Oct 23 | 190 d | 6a |
| Pembroke Township | Apr 19 | Oct 24 | 188 d | 5b |
| Penfield | Apr 21 | Oct 18 | 180 d | 6a |
| Peoria | Apr 16 | Oct 23 | 190 d | 6a |
| Peoria Heights | Apr 16 | Oct 23 | 190 d | 6a |
| Peotone | Apr 23 | Oct 20 | 180 d | 6a |
| Percy | Apr 12 | Oct 22 | 193 d | 7a |
| Perks | Apr 3 | Nov 5 | 216 d | 7a |
| Perry | Apr 18 | Oct 15 | 180 d | 6a |
| Peru | Apr 24 | Oct 18 | 177 d | 5b |
| Pesotum | Apr 15 | Oct 20 | 188 d | 6a |
| Petersburg | Apr 13 | Oct 21 | 191 d | 6a |
| Philo | Apr 19 | Oct 17 | 181 d | 6a |
| Piasa | Apr 14 | Oct 19 | 188 d | 6b |
| Pierron | Apr 6 | Oct 29 | 206 d | 6b |
| Pinckneyville | Apr 6 | Oct 22 | 199 d | 7a |
| Piper City | Apr 25 | Oct 20 | 178 d | 6a |
| Pittsburg | Apr 7 | Oct 26 | 202 d | 7a |
| Pittsfield | Apr 14 | Oct 21 | 190 d | 6a |
| Plainfield | Apr 20 | Oct 22 | 185 d | 5b |
| Plainville | Apr 14 | Oct 23 | 192 d | 6a |
| Plano | Apr 28 | Oct 13 | 168 d | 5b |
| Pleasant Hill | Apr 4 | Nov 1 | 211 d | 6b |
| Pleasant Plains | Apr 19 | Oct 19 | 183 d | 6a |
| Plymouth | Apr 13 | Oct 22 | 192 d | 6a |
| Pocahontas | Apr 6 | Oct 29 | 206 d | 6b |
| Polo | Apr 29 | Oct 7 | 161 d | 5b |
| Pomona | Apr 9 | Oct 22 | 196 d | 7a |
| Pontiac | Apr 16 | Oct 24 | 191 d | 6a |
| Poplar Grove | Apr 30 | Oct 10 | 163 d | 5b |
| Port Byron | Apr 16 | Oct 25 | 192 d | 5b |
| Posen | Apr 10 | Nov 1 | 205 d | 6a |
| Potomac | Apr 22 | Oct 19 | 180 d | 6a |
| Prairie City | Apr 17 | Oct 22 | 188 d | 6a |
| Prairie Du Rocher | Apr 8 | Oct 30 | 205 d | 7a |
| Preemption | Apr 22 | Oct 19 | 180 d | 5b |
| Princeton | Apr 22 | Oct 17 | 178 d | 5b |
| Princeville | Apr 22 | Oct 14 | 175 d | 5b |
| Prophetstown | Apr 26 | Oct 13 | 170 d | 5b |
| Prospect Heights | Apr 19 | Oct 26 | 190 d | 6a |
| Pulaski | Apr 3 | Nov 5 | 216 d | 7a |
| Putnam | Apr 18 | Oct 22 | 187 d | 5b |