Aledo, Illinois · field elev 740 ft
Density Altitude at Mercer County (C00)
Mercer County sits at 740 ft, and even a typical July afternoon (85 °F) only lifts density altitude to about 2,564 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 | 22.2 | −1,588 ft | 31.0 | −964 ft |
| February | 26.3 | −1,296 ft | 35.6 | −644 ft |
| March | 38.2 | −464 ft | 49.1 | 276 ft |
| April | 50.0 | 336 ft | 62.1 | 1,134 ft |
| May | 61.2 | 1,075 ft | 72.7 | 1,814 ft |
| June | 70.7 | 1,687 ft | 81.7 | 2,378 ft |
| July | 74.1 | 1,902 ft | 84.7 | 2,564 ft |
| August | 72.3 | 1,788 ft | 83.1 | 2,465 ft |
| September | 65.1 | 1,328 ft | 76.9 | 2,079 ft |
| October | 52.7 | 516 ft | 64.1 | 1,263 ft |
| November | 39.4 | −382 ft | 49.3 | 289 ft |
| December | 28.0 | −1,175 ft | 36.4 | −589 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 C00
DENSITY ALTITUDE
Field elevation 740 ft — the air behaves like 2,582 ft.
- PRESSURE ALT
- 741 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
- KMLI — Quad Cities International
Moline · elev 590 ft
- C66 — Monmouth Municipal
Monmouth · elev 753 ft
- KGBG — Harrel W Timmons Galesburg Regional
Galesburg · elev 764 ft
- 3G8 — Gen-Airpark
Geneseo · elev 645 ft
- KEZI — Kewanee Municipal
Kewanee · elev 858 ft
- 2C6 — Tri-County
Yates City · elev 661 ft
- KMQB — Macomb Municipal
Macomb · elev 706 ft
- KCTK — Ingersoll
Canton · elev 684 ft
Frequently asked questions
How high does density altitude get at C00 in summer?
On a typical July afternoon — around 85 °F at the nearest NOAA normals station — density altitude at Mercer County reaches roughly 2,564 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 C00 on an average day?
It swings with the seasons: from roughly −1,588 ft at the coldest month's average temperature to about 1,902 ft at the warmest month's — all from a constant field elevation of 740 ft. The month-by-month table above carries the full year.
What is the field elevation of Mercer County?
740 ft MSL, from the FAA NASR airport record (28-day cycle effective 2026-08-06). The identifier is C00 (FAA), in Aledo, Illinois.