Peru, Illinois · field elev 654 ft
Density Altitude at Illinois Valley Regional-Walter A Duncan Field (KVYS)
Illinois Valley Regional-Walter A Duncan Field sits at 654 ft, and even a typical July afternoon (84 °F) only lifts density altitude to about 2,416 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 | 22.0 | −1,710 ft | 30.0 | −1,142 ft |
| February | 26.0 | −1,425 ft | 34.5 | −828 ft |
| March | 37.4 | −627 ft | 47.5 | 62 ft |
| April | 49.3 | 183 ft | 60.9 | 950 ft |
| May | 60.9 | 950 ft | 72.5 | 1,696 ft |
| June | 70.3 | 1,556 ft | 81.3 | 2,248 ft |
| July | 73.4 | 1,753 ft | 84.0 | 2,416 ft |
| August | 71.5 | 1,632 ft | 82.2 | 2,304 ft |
| September | 64.8 | 1,203 ft | 76.9 | 1,973 ft |
| October | 52.5 | 396 ft | 63.9 | 1,145 ft |
| November | 39.2 | −503 ft | 48.4 | 122 ft |
| December | 27.7 | −1,304 ft | 35.5 | −758 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 KVYS
DENSITY ALTITUDE
Field elevation 654 ft — the air behaves like 2,416 ft.
- PRESSURE ALT
- 655 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
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Frequently asked questions
How high does density altitude get at KVYS in summer?
On a typical July afternoon — around 84 °F at the nearest NOAA normals station — density altitude at Illinois Valley Regional-Walter A Duncan Field reaches roughly 2,416 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 KVYS on an average day?
It swings with the seasons: from roughly −1,710 ft at the coldest month's average temperature to about 1,753 ft at the warmest month's — all from a constant field elevation of 654 ft. The month-by-month table above carries the full year.
What is the field elevation of Illinois Valley Regional-Walter A Duncan Field?
654 ft MSL, from the FAA NASR airport record (28-day cycle effective 2026-08-06). The identifier is KVYS (ICAO) / VYS (FAA), in Peru, Illinois.