Zone | Jan. | Feb. | March | April | May | June | July | August | Sept. | Oct. | Nov. | Dec. |
B | 9.5 | 9.4 | 8.8 | 8.8 | 8.7 | 8.3 | 7.1 | 6.7 | 7.7 | 9.1 | 9.8 | 9.3 |