Iowa frost dates: P
| City | Last frost | First frost | Season | Zone |
|---|---|---|---|---|
| Pacific Junction | Apr 23 | Oct 11 | 171 d | 5b |
| Packwood | Apr 27 | Oct 12 | 168 d | 5b |
| Palmer | Apr 26 | Oct 7 | 164 d | 5a |
| Palo | Apr 28 | Oct 12 | 167 d | 5a |
| Panama | Apr 27 | Oct 9 | 165 d | 5b |
| Panora | May 2 | Oct 3 | 154 d | 5a |
| Parkersburg | Apr 27 | Oct 8 | 164 d | 5a |
| Parnell | Apr 28 | Oct 9 | 164 d | 5b |
| Paton | Apr 26 | Oct 9 | 166 d | 5a |
| Patterson | Apr 30 | Oct 3 | 156 d | 5b |
| Paullina | Apr 29 | Oct 10 | 164 d | 5a |
| Pella | Apr 20 | Oct 19 | 182 d | 5b |
| Peosta | Apr 28 | Oct 11 | 166 d | 5a |
| Percival | Apr 18 | Oct 19 | 184 d | 5b |
| Perry | Apr 25 | Oct 10 | 168 d | 5a |
| Persia | Apr 29 | Oct 8 | 162 d | 5b |
| Peru | Apr 30 | Oct 3 | 156 d | 5b |
| Peterson | Apr 30 | Oct 5 | 158 d | 5a |
| Pierson | Apr 30 | Oct 9 | 162 d | 5a |
| Pilot Grove | Apr 17 | Oct 22 | 188 d | 6a |
| Pilot Mound | Apr 28 | Oct 12 | 167 d | 5a |
| Pisgah | May 1 | Oct 3 | 155 d | 5b |
| Plainfield | Apr 29 | Oct 9 | 163 d | 5a |
| Plano | Apr 28 | Oct 14 | 169 d | 5b |
| Pleasant Hill | Apr 18 | Oct 20 | 185 d | 5b |
| Pleasant Valley | Apr 16 | Oct 25 | 192 d | 5b |
| Pleasantville | Apr 20 | Oct 19 | 182 d | 5b |
| Plover | Apr 26 | Oct 7 | 164 d | 5a |
| Plymouth | Apr 29 | Oct 7 | 161 d | 5a |
| Pocahontas | Apr 26 | Oct 7 | 164 d | 5a |
| Polk City | Apr 19 | Oct 18 | 182 d | 5b |
| Pomeroy | Apr 26 | Oct 10 | 167 d | 5a |
| Popejoy | Apr 28 | Oct 10 | 165 d | 5a |
| Portsmouth | Apr 27 | Oct 9 | 165 d | 5b |
| Postville | May 1 | Oct 3 | 155 d | 5a |
| Prairie City | Apr 21 | Oct 15 | 177 d | 5b |
| Prairieburg | May 3 | Oct 7 | 157 d | 5a |
| Prescott | Apr 27 | Oct 12 | 168 d | 5b |
| Preston | Apr 25 | Oct 14 | 172 d | 5a |
| Primghar | Apr 29 | Oct 10 | 164 d | 5a |
| Princeton | Apr 16 | Oct 25 | 192 d | 5b |
| Prole | Apr 24 | Oct 12 | 171 d | 5b |
| Promise City | Apr 21 | Oct 19 | 181 d | 5b |
| Protivin | May 8 | Oct 1 | 146 d | 4b |
| Pulaski | Apr 16 | Oct 22 | 189 d | 5b |