Monmouth, Illinois · field elev 753 ft
Density Altitude at Monmouth Municipal (C66)
Monmouth Municipal sits at 753 ft, and even a typical July afternoon (84 °F) only lifts density altitude to about 2,543 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 | 23.1 | −1,507 ft | 31.4 | −920 ft |
| February | 27.5 | −1,195 ft | 36.2 | −586 ft |
| March | 39.4 | −366 ft | 49.7 | 332 ft |
| April | 51.3 | 439 ft | 62.8 | 1,195 ft |
| May | 61.9 | 1,137 ft | 72.9 | 1,842 ft |
| June | 70.8 | 1,709 ft | 81.2 | 2,363 ft |
| July | 73.8 | 1,899 ft | 84.1 | 2,543 ft |
| August | 72.2 | 1,798 ft | 82.8 | 2,462 ft |
| September | 65.4 | 1,363 ft | 77.3 | 2,120 ft |
| October | 53.5 | 585 ft | 64.8 | 1,325 ft |
| November | 39.9 | −331 ft | 49.2 | 299 ft |
| December | 28.6 | −1,117 ft | 36.5 | −565 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 C66
DENSITY ALTITUDE
Field elevation 753 ft — the air behaves like 2,536 ft.
- PRESSURE ALT
- 754 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 Illinois fields
- KGBG — Harrel W Timmons Galesburg Regional
Galesburg · elev 764 ft
- C00 — Mercer County
Aledo · elev 740 ft
- KMQB — Macomb Municipal
Macomb · elev 706 ft
- 2C6 — Tri-County
Yates City · elev 661 ft
- KMLI — Quad Cities International
Moline · elev 590 ft
- KCTK — Ingersoll
Canton · elev 684 ft
- KEZI — Kewanee Municipal
Kewanee · elev 858 ft
- 3G8 — Gen-Airpark
Geneseo · elev 645 ft
Frequently asked questions
How high does density altitude get at C66 in summer?
On a typical July afternoon — around 84 °F at the nearest NOAA normals station — density altitude at Monmouth Municipal reaches roughly 2,543 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 C66 on an average day?
It swings with the seasons: from roughly −1,507 ft at the coldest month's average temperature to about 1,899 ft at the warmest month's — all from a constant field elevation of 753 ft. The month-by-month table above carries the full year.
What is the field elevation of Monmouth Municipal?
753 ft MSL, from the FAA NASR airport record (28-day cycle effective 2026-08-06). The identifier is C66 (FAA), in Monmouth, Illinois.