Port Of Del Bonita, Montana · field elev 4,336 ft
Density Altitude at Whetstone International (H28)
From a field elevation of 4,336 ft, a typical July afternoon at Whetstone International (76 °F) raises density altitude to about 6,411 ft — solidly into the range where performance charts deserve a close read.
Typical density altitude by month
| Month | Avg temp °F | DA at avg temp | Afternoon high °F | DA on a typical afternoon |
|---|---|---|---|---|
| January | 20.2 | 2,773 ft | 29.5 | 3,414 ft |
| February | 21.9 | 2,891 ft | 31.1 | 3,523 ft |
| March | 28.8 | 3,367 ft | 38.8 | 4,041 ft |
| April | 38.6 | 4,028 ft | 49.8 | 4,764 ft |
| May | 48.6 | 4,686 ft | 61.1 | 5,487 ft ▲ |
| June | 55.6 | 5,138 ft | 67.4 | 5,882 ft ▲ |
| July | 62.4 | 5,569 ft | 76.0 | 6,411 ft ▲ |
| August | 61.4 | 5,506 ft | 75.8 | 6,399 ft ▲ |
| September | 53.5 | 5,003 ft | 66.6 | 5,832 ft ▲ |
| October | 41.1 | 4,194 ft | 52.5 | 4,939 ft |
| November | 28.4 | 3,339 ft | 37.2 | 3,934 ft |
| December | 21.0 | 2,828 ft | 29.6 | 3,421 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 H28
DENSITY ALTITUDE caution
Field elevation 4,336 ft — the air behaves like 6,411 ft.
- PRESSURE ALT
- 4,338 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 Montana fields
- 8S0 — Starr-Browning Airstrip
Browning · elev 4,657 ft
- KCTB — Cut Bank International
Cut Bank · elev 3,858 ft
- 7S8 — Ross International
Sweetgrass · elev 3,553 ft
- KSBX — Shelby
Shelby · elev 3,443 ft
- 7S7 — Valier
Valier · elev 3,826 ft
- 8U2 — Schafer /Usfs/
Schafer · elev 4,856 ft
- S01 — Conrad
Conrad · elev 3,548 ft
- 58S — Whitefish
Whitefish · elev 3,066 ft
Frequently asked questions
How high does density altitude get at H28 in summer?
On a typical July afternoon — around 76 °F at the nearest NOAA normals station — density altitude at Whetstone International reaches roughly 6,411 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 H28 on an average day?
It swings with the seasons: from roughly 2,773 ft at the coldest month's average temperature to about 5,569 ft at the warmest month's — all from a constant field elevation of 4,336 ft. The month-by-month table above carries the full year.
What is the field elevation of Whetstone International?
4,336 ft MSL, from the FAA NASR airport record (28-day cycle effective 2026-08-06). The identifier is H28 (FAA), in Port Of Del Bonita, Montana.