Ideal Broiler House Temperature: Chart by Age and How to Measure It

House temperature is the single variable that most determines a broiler cycle’s outcome. Not feed, not genetics — temperature. Birds chilled in week one never make up the lost weight, and birds overheated in the final week stop eating exactly when growth should be fastest.

This article covers the reference ranges used across the industry, why the targets drop with age, how to measure correctly, and what happens when the target is missed on the high side.

Why targets drop with age

Day-old chicks cannot regulate their own body temperature. Thermoregulation matures at around 10–14 days. Before that, chicks depend entirely on ambient heat — which is why brooding requires high temperatures.

Once thermoregulation works, the situation reverses. Birds produce their own metabolic heat, and that output climbs with body weight. By week five a broiler is a walking heat source. The house no longer needs warming — it needs cooling.

This is the point most often missed: the temperature problem in week one and the temperature problem in the final week run in opposite directions, and solving them requires different equipment.

Temperature and humidity chart by age

These are reference ranges in common industry use. Every strain publishes its own guide — Cobb, Ross and others issue official tables — so always follow the guide for the strain you run.

Age	Reference temperature	Relative humidity
Days 1–3	32–34 °C	60–70%
Days 4–7	30–32 °C	60–70%
Week 2	28–30 °C	60–70%
Week 3	26–28 °C	55–65%
Week 4	22–25 °C	55–65%
Week 5+	20–23 °C	50–65%

Note the humidity column. Temperature without humidity context means little — 30 °C at 50% RH and 30 °C at 85% RH are entirely different environments for a bird, because birds shed heat by evaporation from the respiratory tract. The more humid the air, the harder that evaporation becomes.

Effective temperature: what the bird feels

A thermometer reports air temperature. Birds experience effective temperature — air temperature, humidity and air speed at bird level combined.

Air movement lowers effective temperature by carrying heat away from the body surface. This is the basis of tunnel ventilation: fast-moving air makes birds feel several degrees cooler than the thermometer reads, without cooling the air at all.

That effect has an important limit. Wind chill only works while air temperature stays below the bird’s body temperature. Once house air reaches 35 °C and above, speeding up airflow stops cooling — you are blowing hot air at already-hot birds. At that point the only remaining option is to lower the air temperature itself, not to run the fans harder.

How to measure correctly

The most common measurement error is placing sensors where it is convenient for people rather than where the birds are.

• Measure at bird level. A sensor at chest height reads a different environment from the floor. A gap of several degrees between bird-back level and 1.5 metres is routine.
• Measure at several points along the house. Tunnel houses almost always run a gradient: coolest at the inlet, warmest at the exhaust. One sensor mid-house hides it.
• Measure humidity alongside. Temperature data without RH cannot support a cooling decision.
• Watch the birds, not only the numbers. Evenly spread means comfortable. Huddling means cold. Moving away from each other, wings held out, beaks open — too hot.

What happens when temperature runs high

As house temperature passes the comfort zone, the response is sequential and observable:

1. Activity drops and birds spread apart to reduce heat from neighbours.
2. Wings lift away from the body to expose more surface for heat loss.
3. Feed intake falls. Digestion generates heat, so birds avoid it. This is where growth starts falling behind.
4. Water intake rises sharply, often doubling or more.
5. Panting begins. This is the bird’s main cooling mechanism, but it costs energy and disturbs blood acid-base balance.

The loss is not only in visible mortality. A few days of reduced feed intake in the final week is enough to change the harvest result without a single bird dying.

When the problem arrives

In Indonesia’s tropical lowlands, heat pressure concentrates between 11:00 and 16:00. What makes it hard is the coincidence: the hottest period of the day meets the final weeks of the cycle, when bird weight — and metabolic heat output — is at its peak.

This means a cooling system does not need to run 24 hours. What it needs is the ability to meaningfully lower air temperature for roughly five critical hours a day, over the last few weeks of each cycle.

Options for lowering air temperature

Three approaches are used in Indonesian houses, all working on the same evaporative principle:

• Cooling pads at the inlet — cool the air as it enters. Effective, but they create a gradient: the further from the inlet, the warmer the air.
• Low-pressure fogging — cheap, but large droplets (50 microns and up) land on the litter and cause caking and ammonia risk.
• High-pressure misting (70 bar) — sub-10-micron droplets evaporate before reaching the floor, and nozzle lines can run the length of the house for more even cooling.

All three raise humidity, because that is how evaporative cooling works. In houses where RH is already high, sensor-based control becomes essential — the system must stop before humidity reaches the point where it undermines the bird’s ability to shed heat.

In short

Targets fall from 32–34 °C on day one to 20–23 °C approaching harvest, always read alongside humidity. Measure at bird level and at several points. Use bird behaviour to verify the numbers. And understand that above 35 °C, running the fans harder stops helping — what remains is lowering the air temperature.

If your house struggles to hold temperature between 11:00 and 16:00, see how high-pressure poultry house cooling works, or send the house dimensions, housing type and flock size over WhatsApp. We will size the nozzle requirement and send a cost range.