Full Index:
- Jan. (Low / High)
- Feb. (Low / High)
- Mar. (Low / High)
- Apr. (Low / High)
- May. (Low / High)
- Jun. (Low / High)
- Jul. (Low / High)
- Aug. (Low / High)
- Sep (Low / High)
- Oct. (Low / High)
- Nov. (Low / High)
- Dec. (Low / High)
September record low surface level pressures for the contiguous US