Atomic City, Idaho · field elev 5,073 ft
Density Altitude at Big Southern Butte (U46)
Big Southern Butte is a genuine high-and-hot field: from 5,073 ft of elevation, a typical July afternoon (89 °F) pushes density altitude to about 8,072 ft — the airplane performs like it is 2,999 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 | 16.9 | 3,462 ft | 28.1 | 4,235 ft |
| February | 21.9 | 3,810 ft | 33.3 | 4,586 ft |
| March | 33.7 | 4,613 ft | 46.2 | 5,438 ft ▲ |
| April | 42.6 | 5,203 ft | 57.1 | 6,138 ft ▲ |
| May | 52.0 | 5,813 ft | 67.3 | 6,776 ft ▲ |
| June | 60.5 | 6,352 ft | 77.3 | 7,386 ft ▲ |
| July | 69.3 | 6,899 ft | 88.8 | 8,072 ft ⚠ |
| August | 67.2 | 6,769 ft | 86.7 | 7,948 ft ▲ |
| September | 57.0 | 6,131 ft | 75.7 | 7,290 ft ▲ |
| October | 43.5 | 5,262 ft | 59.6 | 6,295 ft ▲ |
| November | 29.4 | 4,323 ft | 42.3 | 5,184 ft ▲ |
| December | 18.2 | 3,553 ft | 29.3 | 4,316 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 U46
DENSITY ALTITUDE high DA
Field elevation 5,073 ft — the air behaves like 8,084 ft.
- PRESSURE ALT
- 5,075 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 Idaho fields
- U37 — Midway
Atomic City · elev 5,017 ft
- U48 — Coxs Well
Atomic City · elev 5,048 ft
- KAOC — Arco-Butte County
Arco · elev 5,335 ft
- 0U7 — Hollow Top
Carey · elev 5,359 ft
- U97 — Howe
Howe · elev 4,930 ft
- 2U4 — Rockford Municipal
Rockford · elev 4,465 ft
- U92 — Antelope Valley
Moore · elev 6,193 ft
- 1U0 — Bear Trap
Minidoka · elev 4,716 ft
Frequently asked questions
How high does density altitude get at U46 in summer?
On a typical July afternoon — around 89 °F at the nearest NOAA normals station — density altitude at Big Southern Butte reaches roughly 8,072 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 U46 on an average day?
It swings with the seasons: from roughly 3,462 ft at the coldest month's average temperature to about 6,899 ft at the warmest month's — all from a constant field elevation of 5,073 ft. The month-by-month table above carries the full year.
What is the field elevation of Big Southern Butte?
5,073 ft MSL, from the FAA NASR airport record (28-day cycle effective 2026-08-06). The identifier is U46 (FAA), in Atomic City, Idaho.