Gregory, South Dakota · field elev 2,175 ft
Density Altitude at Gregory Municipal/Flynn Field (9D1)
Gregory Municipal/Flynn Field sits at 2,175 ft, and even a typical July afternoon (87 °F) only lifts density altitude to about 4,427 ft — heat still trims performance, but the field rarely turns high-and-hot.
Typical density altitude by month
| Month | Avg temp °F | DA at avg temp | Afternoon high °F | DA on a typical afternoon |
|---|---|---|---|---|
| January | 20.9 | 119 ft | 31.6 | 868 ft |
| February | 24.5 | 373 ft | 35.9 | 1,164 ft |
| March | 34.7 | 1,082 ft | 46.8 | 1,899 ft |
| April | 45.4 | 1,806 ft | 57.6 | 2,609 ft |
| May | 56.9 | 2,564 ft | 68.8 | 3,326 ft |
| June | 67.8 | 3,263 ft | 79.6 | 3,999 ft |
| July | 74.2 | 3,665 ft | 86.6 | 4,427 ft |
| August | 72.0 | 3,527 ft | 84.7 | 4,312 ft |
| September | 63.1 | 2,963 ft | 76.7 | 3,820 ft |
| October | 48.7 | 2,026 ft | 61.6 | 2,867 ft |
| November | 34.9 | 1,096 ft | 46.8 | 1,899 ft |
| December | 24.2 | 352 ft | 34.5 | 1,068 ft |
▲ above 5,000 ft · ⚠ above 8,000 ft. These are planning references at standard pressure and dry air — afternoon humidity and low pressure both push the real number higher. Run today's values below.
Run today’s numbers for 9D1
DENSITY ALTITUDE
Field elevation 2,175 ft — the air behaves like 4,452 ft.
- PRESSURE ALT
- 2,176 ft
- ISA DEVIATION
- —
- RULE-OF-THUMB DA
- —
- AIR DENSITY INDEX
- —
- AIR DENSITY
- —
- WATER · GRAINS/LB
- —
For training and reference · verify with official sources and your POH before flight · no tool on this site renders a go / no-go judgment
Nearby South Dakota fields
- KICR — Winner Regional
Winner · elev 2,032 ft
- 1D3 — Platte Municipal
Platte · elev 1,618 ft
- 9V9 — Chamberlain Municipal
Chamberlain · elev 1,696 ft
- 6A6 — Kimball Municipal
Kimball · elev 1,755 ft
- 8D8 — Lake Andes Municipal
Lake Andes · elev 1,475 ft
- D65 — Corsica Municipal
Corsica · elev 1,580 ft
- KAGZ — Wagner Municipal
Wagner · elev 1,478 ft
- 5P5 — Presho Municipal
Presho · elev 1,760 ft
Frequently asked questions
How high does density altitude get at 9D1 in summer?
On a typical July afternoon — around 87 °F at the nearest NOAA normals station — density altitude at Gregory Municipal/Flynn Field reaches roughly 4,427 ft at standard pressure. Hotter-than-normal days, low pressure, and humidity all push it higher, so run the day's actual numbers before flying.
What is the density altitude at 9D1 on an average day?
It swings with the seasons: from roughly 119 ft at the coldest month's average temperature to about 3,665 ft at the warmest month's — all from a constant field elevation of 2,175 ft. The month-by-month table above carries the full year.
What is the field elevation of Gregory Municipal/Flynn Field?
2,175 ft MSL, from the FAA NASR airport record (28-day cycle effective 2026-08-06). The identifier is 9D1 (FAA), in Gregory, South Dakota.