Hotter Weather, More Heatwaves – How Extreme Weather Affects Fridges and Freezers

June 23, 2026

Hotter Weather, More Heatwaves – How Extreme Weather Affects Fridges and Freezers

In recent years Europe is repeatedly experiencing summer heatwaves, with June heatwaves becoming increasingly common particularly in Spain. Spain’s state weather service, Aemet, reports 10 recorded heatwaves in June in mainland Spain between 2000 and 2025, and just two in the previous 25 years¹.

Other countries are similarly experiencing hotter temperatures and more frequent heatwaves. As well as the impact this has on the lives and health of people, high temperatures can also affect the safety of temperature-sensitive products.

When temperatures rise, fridges and freezers become even more critical to food safety, product quality and compliance. For food businesses, healthcare sites, laboratories, pharmacies, hospitality operators and cold-chain teams, unusually hot weather can place refrigeration equipment under additional pressure. The unit may still appear to be running normally, but behind the scenes the system is often working harder to maintain the required temperature.

This matters because chilled and frozen products rely on stable storage conditions. If a fridge or freezer can’t remove heat quickly enough, internal temperatures can rise. Even short periods outside the correct temperature range can increase food safety risk, affect product quality, reduce shelf life or create compliance issues.

Understanding how refrigeration systems operate, and why hot weather can make their job more difficult, helps businesses prepare before problems occur.

How fridges and freezers normally work

Most commercial fridges and freezers operate using a vapour compression refrigeration cycle. While the equipment can vary in size, from an upright fridge to a walk-in freezer or cold room, the basic principle is the same.

The purpose of the system is to remove heat from inside the cabinet, room or storage area and release that heat outside the cooled space. It does not “create cold” in the way many people imagine. Instead, it continuously moves heat from one place to another.

The main components involved are:

The evaporator: This sits inside the cooled area. Refrigerant passes through the evaporator at a low temperature and absorbs heat from the air inside the fridge or freezer.
The compressor: The compressor pumps refrigerant around the system. It raises the pressure and temperature of the refrigerant so that the absorbed heat can be released.
The condenser: The condenser is usually located outside the chilled space, often at the back, top or external plant area of the unit. Its job is to reject heat into the surrounding air.
The expansion valve or metering device: This controls the flow of refrigerant into the evaporator and reduces its pressure, allowing it to absorb heat again.
Fans and controls: Fans move air across the evaporator and condenser coils. Sensors and thermostats monitor temperature and tell the system when to switch on, run harder or switch off.

During normal operation, the thermostat detects when the internal temperature rises above the set point. The compressor starts, refrigerant circulates and the system removes heat until the required temperature is reached again. The compressor then cycles off or reduces output, depending on the type of system.

In a well-maintained unit, this process happens continuously throughout the day. Doors open, warm air enters, products are loaded, and the system responds by removing the extra heat.

What changes during extremely hot weather?

During hot weather, the fridge or freezer still works in the same technical way. The refrigeration cycle does not change. However, the conditions around the equipment change significantly.

A fridge that performs adequately in mild conditions may struggle when temperatures rise.

The most important factor is the difference between the temperature inside the unit and the temperature outside it. A fridge may be trying to hold food at around 5°C or below, while the surrounding room might be 28°C or higher. A freezer may be trying to maintain frozen products at around -18°C while rejecting heat into very warm ambient air.

This wider temperature difference creates a higher heat load. More heat enters the cabinet through door openings, walls, seals and product loading. At the same time, the condenser has to reject heat into air that’s already warm. That makes the process less efficient.

In practical terms, the system may need to run for longer periods. The compressor may cycle on more frequently. Fans may operate more often. Defrost cycles may become more important. Any weakness in the equipment, such as dirty condenser coils, worn door seals, poor airflow or low refrigerant charge, can become more noticeable during hot weather.

A fridge or freezer that performs adequately in mild conditions may struggle when temperatures rise.

The compressor works harder

The compressor is one of the hardest-working parts of a refrigeration system. During hot weather, it may be under increased pressure because the system needs to remove more heat and run for longer.

When the condenser is exposed to high ambient temperatures, the refrigerant may not reject heat as easily. This can increase the pressure on the high side of the system. The compressor then has to work harder to move refrigerant and maintain the required cooling effect.

Longer run times can increase wear. Higher operating pressures can increase stress. Electrical components may also run hotter. If the compressor is already ageing, poorly maintained or operating in a poorly ventilated area, unusually hot weather can increase the likelihood of failure.

This does not mean that every fridge or freezer will break down during a heatwave. Well-designed, well-maintained equipment should be able to cope with expected operating conditions. However, hot weather reduces the margin for error. It can expose problems that were previously hidden.

The condenser has to reject heat into hotter air

The condenser is responsible for releasing heat from the refrigeration system into the surrounding environment. It works best when there is good airflow and a reasonable difference between the condenser temperature and the surrounding air temperature.

During extremely hot weather, this becomes more difficult. The air around the condenser is warmer, so heat transfer is less effective. If the condenser coil is dusty, blocked or located in a cramped plant room, the problem can become worse.

Poor condenser performance can lead to higher head pressure, longer compressor run times and reduced cooling capacity. In some cases, the system may trip on high pressure to protect itself. This can leave the fridge, freezer or cold room unable to maintain temperature until the fault is resolved.

For this reason, condenser cleaning and ventilation are particularly important before and during periods of hot weather.

Door seals, insulation and airflow become more important

Hot weather also increases the importance of the basic physical condition of the unit.

Door seals help prevent warm air entering the fridge or freezer. If seals are cracked, loose or damaged, warm air can leak into the cabinet. This forces the system to remove more heat and may lead to condensation, ice build-up or unstable internal temperatures.

Insulation also plays a key role. The walls, doors and panels of the unit are designed to slow heat transfer. If insulation is damaged or panels are poorly fitted, more heat enters the cooled space.

Airflow inside the unit is another important factor. If stock is packed too tightly or vents are blocked, cold air cannot circulate properly. This can create warm spots, even if the temperature sensor shows that part of the unit is within range. During hot weather, poor airflow can become a bigger issue because the system has less spare cooling capacity.

Fans and evaporators may be under more pressure

Evaporator fans circulate cold air around the storage area. Condenser fans help remove heat from the system. During hot weather, both may run more frequently or for longer periods.

If a fan motor is weak, obstructed or failing, the refrigeration system may not perform properly. Reduced airflow across the evaporator can affect cooling inside the cabinet. Reduced airflow across the condenser can prevent heat from being rejected effectively.

The evaporator itself can also be affected by moisture. When warm, humid air enters a fridge or freezer, especially through frequent door openings, moisture can condense or freeze on the evaporator coil. In freezers, this can contribute to ice build-up. Excessive frost can restrict airflow and reduce the system’s ability to absorb heat.

Defrost systems are designed to manage this, but if defrost cycles are not working correctly, hot weather and high humidity can make the issue more visible.

Are fridges and freezers more likely to break down in hot weather?

It’s possible, especially if they are already under-maintained, overloaded or operating in poor conditions.

Hot weather does not automatically cause refrigeration failure. Commercial units are designed to operate within specified ambient temperature ranges. However, when ambient temperature rises, the system has to work harder. Components may experience longer run times, higher pressures and greater thermal stress.

Problems that may be manageable in cooler weather can become critical in hot weather. Examples include:

Dirty condenser coils
Blocked airflow around the unit
Damaged door seals
Poorly closing doors
Overloaded cabinets
Frequent door openings
Faulty fans
Incorrect thermostat settings
Low refrigerant charge
Ageing compressors
Poorly maintained defrost systems

The risk isn’t just that a unit stops working completely. A more common issue is that it slowly struggles to maintain temperature. This can be harder to spot without continuous monitoring because the unit may still sound as if it is running.

The risk to chilled and frozen products

Higher temperatures can allow harmful bacteria to grow more quickly around temperature-sensitive food in storage.

When fridges and freezers struggle, product temperature can rise. This creates several risks.

For chilled food, higher temperatures can allow harmful bacteria to grow more quickly². Even where food remains visually unchanged, the safety risk may increase if it has been held outside the required temperature range.

For frozen food, temperature rise can affect quality and safety. Partial thawing and refreezing can damage texture, increase ice crystal formation and reduce product integrity. In some cases, frozen products may no longer be suitable for sale or use.

For healthcare, pharmacy, laboratory and life sciences environments, the stakes can be just as significant. Medicines, vaccines, samples, reagents and other temperature-sensitive materials may have strict storage requirements. A temperature excursion can compromise product stability, create documentation challenges and lead to costly wastage.

In any regulated environment, the issue is not only whether a product feels cold or frozen. The question is whether it has remained within the approved temperature range for the required period.

Why manual checks may not be enough

During hot weather, temperature can change quickly. A manual check carried out once or twice a day may miss an overnight excursion, a lunchtime door issue or a gradual rise caused by a failing component.

By the time a member of staff notices a problem, the unit may already have been outside range for several hours. Without a clear temperature record, it can be difficult to know when the issue started, how long products were affected and what has been happening at each CCP³.

Continuous temperature monitoring gives teams better visibility. Automated alerts can warn staff when temperatures move outside agreed limits, allowing them to act before stock, samples or medicines are compromised. Digital records also support audit readiness by showing the temperature history and the response taken.

Practical steps during hot weather

Businesses can reduce risk by preparing refrigeration equipment before hot weather arrives and increasing vigilance during warm periods.

Key actions include:

Check that fridges, freezers and cold rooms are operating at the correct set temperatures⁴
Inspect door seals and replace damaged seals promptly
Avoid overloading cabinets or blocking vents
Minimise unnecessary door openings
Allow hot food or deliveries to cool appropriately before loading, where safe and suitable
Check that fans are operating correctly
Review defrost performance on freezers
Ensure condenser and evaporator coils are inspected and cleaned as part of routine refrigeration maintenance, and check that airflow around the equipment is not restricted⁵
Keep plant rooms and back-of-house areas as cool and ventilated as possible
Use automated monitoring and alerts to detect issues early
Record corrective actions when temperatures move outside limits

Hot weather makes monitoring essential

Extremely hot weather places additional pressure on fridges and freezers. The refrigeration cycle remains the same, but units must work harder to remove heat and maintain safe storage conditions. Compressors, condensers, fans, seals, evaporators and defrost systems all become more important when ambient temperatures rise.

Ensure that monitoring processes and systems are in place to alert staff if equipment is struggling or fails, potentially leading to products moving outside safe or approved temperature ranges. Wastage, compliance issues, product degradation and financial loss can all be the result of equipment failure, which could otherwise be averted if reliable monitoring is in place.

Contact Kelsius to learn more about automated temperature monitoring with real-time alerts.