North Dakota frost dates: B
| City | Last frost | First frost | Season | Zone |
|---|---|---|---|---|
| Baldwin | May 10 | Sep 30 | 143 d | 4a |
| Balfour | May 12 | Sep 27 | 138 d | 4a |
| Balta | May 11 | Sep 28 | 140 d | 4a |
| Bantry | May 15 | Sep 25 | 133 d | 3b |
| Barney | May 2 | Oct 6 | 157 d | 4a |
| Bathgate | May 12 | Sep 30 | 141 d | 3b |
| Beach | May 16 | Sep 26 | 133 d | 4a |
| Belcourt | May 19 | Sep 24 | 128 d | 3b |
| Belfield | May 9 | Sep 30 | 144 d | 4b |
| Benedict | May 10 | Sep 28 | 141 d | 4a |
| Berlin | May 10 | Sep 28 | 141 d | 4b |
| Berthold | May 11 | Sep 29 | 141 d | 4a |
| Beulah | May 21 | Sep 20 | 122 d | 4a |
| Binford | May 12 | Sep 28 | 139 d | 4a |
| Bisbee | May 22 | Sep 20 | 121 d | 3b |
| Bismarck | May 10 | Sep 30 | 143 d | 4a |
| Blanchard | May 2 | Oct 9 | 160 d | 4a |
| Bottineau | May 15 | Sep 25 | 133 d | 3b |
| Bowbells | May 20 | Sep 19 | 122 d | 4a |
| Bowdon | May 13 | Sep 29 | 139 d | 4a |
| Bowman | May 16 | Sep 25 | 132 d | 4b |
| Braddock | May 11 | Sep 29 | 141 d | 4a |
| Brocket | May 15 | Sep 22 | 130 d | 4a |
| Buchanan | May 11 | Sep 28 | 140 d | 4b |
| Buffalo | May 9 | Oct 1 | 145 d | 4a |
| Burlington | May 10 | Oct 1 | 144 d | 4a |
| Butte | May 16 | Sep 28 | 135 d | 4a |
| Buxton | May 2 | Oct 9 | 160 d | 4a |