Idaho City, Idaho · field elev 3,920 ft
Density Altitude at Idaho City Usfs (U98)
From a field elevation of 3,920 ft, a typical July afternoon at Idaho City Usfs (87 °F) raises density altitude to about 6,576 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 | 24.4 | 2,546 ft | 35.3 | 3,291 ft |
| February | 28.2 | 2,808 ft | 40.5 | 3,640 ft |
| March | 34.9 | 3,264 ft | 47.8 | 4,121 ft |
| April | 41.7 | 3,719 ft | 56.0 | 4,652 ft |
| May | 50.5 | 4,297 ft | 66.4 | 5,311 ft ▲ |
| June | 57.8 | 4,768 ft | 75.3 | 5,862 ft ▲ |
| July | 66.3 | 5,305 ft | 87.1 | 6,576 ft ▲ |
| August | 65.0 | 5,223 ft | 86.3 | 6,528 ft ▲ |
| September | 56.1 | 4,659 ft | 76.5 | 5,936 ft ▲ |
| October | 44.5 | 3,905 ft | 61.5 | 5,003 ft ▲ |
| November | 32.5 | 3,101 ft | 44.2 | 3,885 ft |
| December | 24.3 | 2,539 ft | 34.6 | 3,244 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 U98
DENSITY ALTITUDE caution
Field elevation 3,920 ft — the air behaves like 6,570 ft.
- PRESSURE ALT
- 3,922 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
- U88 — Garden Valley
Garden Valley · elev 3,177 ft
- KBOI — Boise Air Trml/Gowen Field
Boise · elev 2,872 ft
- 52U — Weatherby Usfs
Atlanta · elev 4,503 ft
- 2U0 — Smith Prairie
Prairie · elev 4,958 ft
- U45 — Graham Usfs
Atlanta · elev 5,726 ft
- S78 — Emmett Municipal
Emmett · elev 2,354 ft
- 0U1 — Warm Springs Creek
Lowman · elev 4,831 ft
- 55H — Atlanta
Atlanta · elev 5,500 ft
Frequently asked questions
How high does density altitude get at U98 in summer?
On a typical July afternoon — around 87 °F at the nearest NOAA normals station — density altitude at Idaho City Usfs reaches roughly 6,576 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 U98 on an average day?
It swings with the seasons: from roughly 2,539 ft at the coldest month's average temperature to about 5,305 ft at the warmest month's — all from a constant field elevation of 3,920 ft. The month-by-month table above carries the full year.
What is the field elevation of Idaho City Usfs?
3,920 ft MSL, from the FAA NASR airport record (28-day cycle effective 2026-08-06). The identifier is U98 (FAA), in Idaho City, Idaho.