The short, practical answer: set your forced-air incubator to 99.5°F (37.5°C). For a still-air incubator, measure at the top of the eggs and aim for 101–102°F (38.3–38.8°C). That’s the foundation of reliable hatches. If you’re new to incubation, skim this page first, then dive into our First-Timer’s Guide for a complete start-to-finish walkthrough.
Ideal Temperature for Chicken Eggs
Standard Recommended Range (99.5°F / 37.5°C)
99.5°F (37.5°C) is the “sweet spot” for chicken embryos in a forced-air environment. It mirrors the hen’s brood temperature and keeps development on schedule.
Still-Air vs. Forced-Air Incubators
- Forced-air: Set to 99.5°F (37.5°C) and keep the fan unobstructed for even heat.
- Still-air: Warm air stratifies, so measure at egg-top height. Target 101–102°F (38.3–38.8°C).
Not sure how internal airflow affects temperature readings? Review How an Incubator Works to understand heat, humidity, turning, and ventilation as one system.
Temperature Changes During Incubation Stages
Day 1–18 (Development Stage)
Maintain a steady 99.5°F (forced-air) or 101–102°F (still-air). Consistency beats micro-tweaking—avoid chasing decimal points unless your readings drift for hours.
Day 19–21 (Lockdown & Hatching)
Slight short-term dips (e.g., to 98.5–99°F) can be tolerated during lockdown, but prevent spikes or prolonged drops. Close the lid and let chicks work—opening invites heat/humidity loss. For lockdown fundamentals, see our Candling & Timing Guide and the final-stage notes in the Turkey / Duck guides.
Temperature & Humidity Work Together
Temperature drives growth; humidity regulates moisture loss. Too dry → sticky chicks and “shrink-wrap.” Too wet → excess fluid and drowning risk. Get your humidity basics in our post-hatch & humidity notes.
Why Temperature Consistency Matters
When Temperature Runs Low
- Development slows; hatches run late.
- Yolk absorption may lag; chicks can emerge weak.
When Temperature Runs High
- Embryos develop too fast under stress.
- Higher risk of deformities or late-stage mortality.
Bottom Line for Hatchability
Sustained deviations of even ~1°F over several hours can meaningfully reduce hatch rates. The best strategy is a correctly calibrated setting you rarely need to touch.
Factors That Nudge Your Incubator’s Temperature
Room Environment & Placement
Avoid drafts, vents, heaters, or direct sun. Even the most advanced units will drift if the room swings.
Thermometer Accuracy & Calibration
Don’t trust a single sensor. Cross-check your incubator’s display with a calibrated digital thermometer placed at egg level.
Opening the Lid Too Often
Every lift dumps heat and humidity. Batch your checks and candle on the recommended days—see our Candling Timeline.
Tips to Lock In the Correct Temperature
- Run two thermometers and one digital hygrometer; trust the consensus.
- Place the incubator in a stable, interior space away from windows.
- Make small, gradual changes (0.1–0.2°F) and re-check in 30–60 minutes.
- Measure at egg height—not near the lid or sidewall.
- Pre-heat for several hours before setting eggs; log readings.
Quick Reference Table
| Incubator Type |
Ideal Temp |
Too Low → Risk |
Too High → Risk |
|---|---|---|---|
| Forced-Air |
99.5°F (37.5°C) |
Late hatch, weak chicks |
Overheating, deformities |
| Still-Air (top of eggs) |
101–102°F (38.3–38.8°C) |
Cold spots, uneven growth |
Embryo death, early hatch |
Tip: A “good enough and stable” setting beats constant micro-adjustments. Log data and look for trends before touching the dial.
Common Mistakes Beginners Make
- Running a still-air unit at 99.5°F (too cool at egg top).
- Trusting one uncalibrated thermometer.
- Chasing decimals every hour—causing more swings.
- Opening during lockdown “just to check.”
- Ignoring humidity while fixing temperature.
Watch: How to Set Incubator Temperature
Troubleshooting: Temperature Drifts & Power Outages
Minor Drifts (±0.5–1.0°F)
- Confirm with two thermometers at egg level.
- Look for room drafts or sun patches; relocate if needed.
- Adjust by small increments and wait for equilibrium.
Significant Swings (>1°F for hours)
- Inspect fan, vents, and water channels (humidity can influence heat balance).
- Check that the incubator isn’t over-packed—crowding creates hot/cold zones.
- Verify outlet voltage or try a different circuit.
Power Outages
| Scenario |
Action |
|---|---|
| Brief outage (<30 min) |
Keep lid closed; wrap the unit with towels to retain heat. |
| Longer outage |
Use battery backup or generator; avoid opening the lid. |
| Prevention |
Have a backup plan and practice it before setting eggs. |
Related Reading (Internal)
- How an Incubator Works: The Science Behind Success
- Candling Fertile Eggs: Timeline & Key Signs
- First-Timer’s Incubation Guide
- How to Hatch Turkey Eggs
- Duck Eggs Incubation Guide
- Post-Hatch Care for Chicks
FAQ: Chicken Egg Incubator Temperature
Can I just set 100°F and forget it?
A reading near 100°F won’t crash a hatch, but prolonged time above 100°F increases risk. If you can hold 99.5°F steadily, do it.
My room swings a lot—what helps the most?
Interior placement, fewer drafts, and a closed door often beat constant dial changes. Stable room → stable incubator.
Do bantam or large fowl need a different temperature?
No—99.5°F is standard for forced-air across chicken sizes. Humidity and turning cadence matter more than changing temperature.
Why does the top read warmer than the tray?
Heat stratifies, especially in still-air models. Always measure at egg height and don’t over-stack trays.
What’s “lockdown” and should I open the lid?
Lockdown starts Day 19: stop turning, increase humidity, and keep the lid shut. Opening creates shrink-wrap risk for pipping chicks. Review the timing in our candling guide.
Final Thoughts
The golden rule for chicken eggs: 99.5°F (37.5°C) forced-air, or 101–102°F still-air measured at egg-top height. Calibrate once, monitor calmly, and resist unnecessary tweaks. Pair steady temperature with appropriate humidity and you’ll give every chick a strong start.
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