Cahokia/St Louis, Illinois · field elev 413 ft
Density Altitude at St Louis Downtown (KCPS)
St Louis Downtown sits at 413 ft, and even a typical July afternoon (89 °F) only lifts density altitude to about 2,429 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 | 32.1 | −1,296 ft | 40.2 | −734 ft |
| February | 36.6 | −982 ft | 45.6 | −366 ft |
| March | 46.1 | −332 ft | 56.3 | 350 ft |
| April | 56.5 | 364 ft | 67.5 | 1,080 ft |
| May | 66.6 | 1,022 ft | 76.7 | 1,666 ft |
| June | 75.2 | 1,571 ft | 85.7 | 2,227 ft |
| July | 78.9 | 1,804 ft | 89.0 | 2,429 ft |
| August | 76.9 | 1,678 ft | 87.8 | 2,356 ft |
| September | 68.9 | 1,170 ft | 80.7 | 1,916 ft |
| October | 57.7 | 443 ft | 69.4 | 1,202 ft |
| November | 45.6 | −366 ft | 55.3 | 284 ft |
| December | 36.4 | −996 ft | 44.3 | −454 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 KCPS
DENSITY ALTITUDE
Field elevation 413 ft — the air behaves like 2,429 ft.
- PRESSURE ALT
- 414 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
- KBLV — Scott AFB/Midamerica St Louis
Belleville · elev 459 ft
- KALN — St Louis Regional
Alton/St Louis · elev 544 ft
- H07 — Highland-Winet
Highland · elev 537 ft
- KSAR — Sparta Community-Hunter Field
Sparta · elev 538 ft
- KGRE — Greenville
Greenville · elev 541 ft
- 3LF — Litchfield Municipal
Litchfield · elev 691 ft
- KENL — Centralia Municipal
Centralia · elev 534 ft
- KPJY — Pinckneyville/Du Quoin
Pinckneyville · elev 400 ft
Frequently asked questions
How high does density altitude get at KCPS in summer?
On a typical July afternoon — around 89 °F at the nearest NOAA normals station — density altitude at St Louis Downtown reaches roughly 2,429 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 KCPS on an average day?
It swings with the seasons: from roughly −1,296 ft at the coldest month's average temperature to about 1,804 ft at the warmest month's — all from a constant field elevation of 413 ft. The month-by-month table above carries the full year.
What is the field elevation of St Louis Downtown?
413 ft MSL, from the FAA NASR airport record (28-day cycle effective 2026-08-06). The identifier is KCPS (ICAO) / CPS (FAA), in Cahokia/St Louis, Illinois.