Geneseo, Illinois · field elev 645 ft
Density Altitude at Gen-Airpark (3G8)
Gen-Airpark sits at 645 ft, and even a typical July afternoon (86 °F) only lifts density altitude to about 2,510 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 | 22.7 | −1,671 ft | 30.8 | −1,097 ft |
| February | 27.2 | −1,351 ft | 35.7 | −755 ft |
| March | 39.1 | −521 ft | 48.9 | 145 ft |
| April | 51.1 | 292 ft | 62.2 | 1,023 ft |
| May | 62.6 | 1,049 ft | 73.7 | 1,761 ft |
| June | 72.2 | 1,666 ft | 82.8 | 2,330 ft |
| July | 75.4 | 1,868 ft | 85.7 | 2,510 ft |
| August | 73.1 | 1,723 ft | 83.4 | 2,368 ft |
| September | 65.8 | 1,256 ft | 77.1 | 1,975 ft |
| October | 53.4 | 445 ft | 64.0 | 1,140 ft |
| November | 39.8 | −473 ft | 48.8 | 138 ft |
| December | 28.2 | −1,280 ft | 35.9 | −742 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 3G8
DENSITY ALTITUDE
Field elevation 645 ft — the air behaves like 2,528 ft.
- PRESSURE ALT
- 646 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
- KEZI — Kewanee Municipal
Kewanee · elev 858 ft
- KMLI — Quad Cities International
Moline · elev 590 ft
- KSQI — Whiteside County/Jos H Bittorf Field
Sterling/Rockfalls · elev 648 ft
- C00 — Mercer County
Aledo · elev 740 ft
- KGBG — Harrel W Timmons Galesburg Regional
Galesburg · elev 764 ft
- KSFY — Tri-Township
Savanna · elev 616 ft
- C73 — Dixon Municipal-Charles R Walgreen Field
Dixon · elev 785 ft
- C66 — Monmouth Municipal
Monmouth · elev 753 ft
Frequently asked questions
How high does density altitude get at 3G8 in summer?
On a typical July afternoon — around 86 °F at the nearest NOAA normals station — density altitude at Gen-Airpark reaches roughly 2,510 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 3G8 on an average day?
It swings with the seasons: from roughly −1,671 ft at the coldest month's average temperature to about 1,868 ft at the warmest month's — all from a constant field elevation of 645 ft. The month-by-month table above carries the full year.
What is the field elevation of Gen-Airpark?
645 ft MSL, from the FAA NASR airport record (28-day cycle effective 2026-08-06). The identifier is 3G8 (FAA), in Geneseo, Illinois.