Butte, Montana · field elev 5,551 ft
Density Altitude at Bert Mooney (KBTM)
Bert Mooney is a genuine high-and-hot field: from 5,551 ft of elevation, a typical July afternoon (81 °F) pushes density altitude to about 8,206 ft — the airplane performs like it is 2,655 ft above the field before the wheels roll.
Typical density altitude by month
| Month | Avg temp °F | DA at avg temp | Afternoon high °F | DA on a typical afternoon |
|---|---|---|---|---|
| January | 20.0 | 4,275 ft | 32.1 | 5,098 ft ▲ |
| February | 22.2 | 4,426 ft | 34.6 | 5,265 ft ▲ |
| March | 31.6 | 5,065 ft | 43.7 | 5,865 ft ▲ |
| April | 38.7 | 5,537 ft | 51.1 | 6,342 ft ▲ |
| May | 47.6 | 6,117 ft | 61.0 | 6,968 ft ▲ |
| June | 55.5 | 6,622 ft | 70.0 | 7,524 ft ▲ |
| July | 63.6 | 7,130 ft | 81.3 | 8,206 ft ⚠ |
| August | 61.8 | 7,018 ft | 79.8 | 8,117 ft ⚠ |
| September | 52.8 | 6,451 ft | 69.1 | 7,469 ft ▲ |
| October | 40.6 | 5,662 ft | 54.3 | 6,546 ft ▲ |
| November | 27.8 | 4,808 ft | 40.2 | 5,636 ft ▲ |
| December | 19.0 | 4,205 ft | 30.7 | 5,004 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 KBTM
DENSITY ALTITUDE high DA
Field elevation 5,551 ft — the air behaves like 8,188 ft.
- PRESSURE ALT
- 5,553 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
- 3U3 — Bowman Field
Anaconda · elev 5,034 ft
- 3U9 — Boulder
Boulder · elev 4,968 ft
- 02T — Wise River
Wise River · elev 5,830 ft
- KRVF — Ruby Valley Field
Twin Bridges · elev 4,789 ft
- 38S — Deer Lodge-City-County
Deer Lodge · elev 4,693 ft
- 9S5 — Three Forks
Three Forks · elev 4,089 ft
- U05 — Riddick Field
Philipsburg · elev 5,219 ft
- KDLN — Dillon
Dillon · elev 5,245 ft
Frequently asked questions
How high does density altitude get at KBTM in summer?
On a typical July afternoon — around 81 °F at the nearest NOAA normals station — density altitude at Bert Mooney reaches roughly 8,206 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 KBTM on an average day?
It swings with the seasons: from roughly 4,205 ft at the coldest month's average temperature to about 7,130 ft at the warmest month's — all from a constant field elevation of 5,551 ft. The month-by-month table above carries the full year.
What is the field elevation of Bert Mooney?
5,551 ft MSL, from the FAA NASR airport record (28-day cycle effective 2026-08-06). The identifier is KBTM (ICAO) / BTM (FAA), in Butte, Montana.