Cave Junction, Oregon · field elev 1,394 ft
Density Altitude at Illinois Valley (3S4)
Illinois Valley sits at 1,394 ft, and even a typical July afternoon (94 °F) only lifts density altitude to about 3,937 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 | 40.7 | 520 ft | 48.9 | 1,073 ft |
| February | 44.0 | 744 ft | 54.6 | 1,450 ft |
| March | 47.3 | 966 ft | 60.2 | 1,816 ft |
| April | 51.6 | 1,252 ft | 66.6 | 2,228 ft |
| May | 58.9 | 1,731 ft | 75.5 | 2,791 ft |
| June | 65.0 | 2,126 ft | 83.5 | 3,287 ft |
| July | 73.1 | 2,640 ft | 94.2 | 3,937 ft |
| August | 71.6 | 2,546 ft | 93.8 | 3,913 ft |
| September | 65.7 | 2,170 ft | 87.1 | 3,508 ft |
| October | 55.3 | 1,496 ft | 71.9 | 2,565 ft |
| November | 45.5 | 845 ft | 55.2 | 1,489 ft |
| December | 39.9 | 466 ft | 47.3 | 966 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 3S4
DENSITY ALTITUDE
Field elevation 1,394 ft — the air behaves like 3,925 ft.
- PRESSURE ALT
- 1,395 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 Oregon fields
- KBOK — Brookings
Brookings · elev 462 ft
- 3S8 — Grants Pass
Grants Pass · elev 1,130 ft
- 4S1 — Gold Beach Municipal
Gold Beach · elev 21 ft
- KMFR — Rogue Valley International/Medford
Medford · elev 1,335 ft
- S03 — Ashland Municipal/Sumner Parker Field
Ashland · elev 1,889 ft
- 6S6 — Powers
Powers · elev 326 ft
- 16S — Myrtle Creek Municipal
Myrtle Creek · elev 619 ft
- 24S — Pinehurst State
Pinehurst · elev 3,643 ft
Frequently asked questions
How high does density altitude get at 3S4 in summer?
On a typical July afternoon — around 94 °F at the nearest NOAA normals station — density altitude at Illinois Valley reaches roughly 3,937 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 3S4 on an average day?
It swings with the seasons: from roughly 466 ft at the coldest month's average temperature to about 2,640 ft at the warmest month's — all from a constant field elevation of 1,394 ft. The month-by-month table above carries the full year.
What is the field elevation of Illinois Valley?
1,394 ft MSL, from the FAA NASR airport record (28-day cycle effective 2026-08-06). The identifier is 3S4 (FAA), in Cave Junction, Oregon.