Poplar Grove, Illinois · field elev 857 ft
Density Altitude at Poplar Grove (C77)
Poplar Grove sits at 857 ft, and even a typical July afternoon (84 °F) only lifts density altitude to about 2,632 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 | 20.9 | −1,534 ft | 29.2 | −945 ft |
| February | 24.5 | −1,277 ft | 33.2 | −665 ft |
| March | 35.4 | −512 ft | 44.9 | 138 ft |
| April | 47.4 | 307 ft | 58.6 | 1,050 ft |
| May | 58.7 | 1,056 ft | 70.2 | 1,798 ft |
| June | 68.6 | 1,696 ft | 79.9 | 2,409 ft |
| July | 72.6 | 1,951 ft | 83.5 | 2,632 ft |
| August | 70.7 | 1,830 ft | 81.8 | 2,527 ft |
| September | 63.6 | 1,375 ft | 75.4 | 2,128 ft |
| October | 51.2 | 561 ft | 62.4 | 1,297 ft |
| November | 38.0 | −332 ft | 46.9 | 273 ft |
| December | 26.5 | −1,135 ft | 34.5 | −574 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 C77
DENSITY ALTITUDE
Field elevation 857 ft — the air behaves like 2,663 ft.
- PRESSURE ALT
- 858 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 C77 in summer?
On a typical July afternoon — around 84 °F at the nearest NOAA normals station — density altitude at Poplar Grove reaches roughly 2,632 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 C77 on an average day?
It swings with the seasons: from roughly −1,534 ft at the coldest month's average temperature to about 1,951 ft at the warmest month's — all from a constant field elevation of 857 ft. The month-by-month table above carries the full year.
What is the field elevation of Poplar Grove?
857 ft MSL, from the FAA NASR airport record (28-day cycle effective 2026-08-06). The identifier is C77 (FAA), in Poplar Grove, Illinois.