Almost everybody looking this up expects a number and there is not one in law. The regulations require a REASONABLE temperature indoors and leave the figure to the guidance, and outdoors they set no figure at all. That sounds like a gap and is not, because the thing that makes somebody cold is not the air temperature alone: it is the air temperature, what they are wearing, how hard they are working, whether there is a draught, and how long they are in it.
What the regulations require instead of a number
The workplace regulations require the temperature in indoor workplaces to be reasonable during working hours, and that word is the whole of the duty. There is no minimum and no maximum written into the regulations, so nobody has a legal right to go home at a particular reading, and equally no employer can point at a thermometer and say the duty is discharged. What backs it up is the general duty to assess risk, so where cold is a foreseeable risk to health the employer has to assess it and act on what the assessment finds. Two consequences follow. A workplace at fifteen degrees with sedentary work is a problem to be fixed even though no number was breached. And a cold store at minus twenty is lawful, because the duty is about controlling the exposure rather than removing the cold.
What the approved code of practice actually suggests
The guidance that accompanies the regulations gives the figures people are usually quoting: normally at least sixteen degrees in an indoor workplace, or thirteen degrees where the work involves severe physical effort. Those are suggestions rather than limits, and they come with two qualifications worth knowing. They apply to the air temperature in the workplace rather than to a reading taken at a draughty door, and they assume people are dressed for the work and not standing in a through breeze. Where the work cannot reasonably be done at those temperatures, for instance in food production or a chilled area, the guidance expects the employer to do everything reasonable to make the conditions comfortable, which is where clothing, breaks, rotation and localised heating come in rather than the thermostat.
Outdoor and cold store work, where the numbers stop helping
Outdoors there is no figure at all and the risks are different in kind. Wind removes heat far faster than still air of the same temperature, wet clothing removes it faster again, and the first thing to go is not core temperature but dexterity and judgement, which is why cold shows up as an accident rather than as illness. In a cold store the exposure is predictable and the controls are the obvious ones written down: insulated clothing that is actually available in the right sizes, gloves that allow the task, limits on continuous exposure with warm breaks timed rather than taken when somebody remembers, and a rule about working alone. Two groups need naming in the assessment: anybody with a circulatory condition or on medication that affects circulation, and anybody using vibrating tools, because cold and vibration together make hand arm vibration damage worse.
A thermal comfort assessment, and what it produces
Thermal comfort is assessed on six factors rather than one: air temperature, radiant temperature from surfaces and sun, air velocity, humidity, the insulation of the clothing being worn and the metabolic heat of the work itself. That is why two people in one room disagree, and why a single reading settles nothing. The assessment is a walk round with the six factors in mind, a conversation with the people doing the work, and a record of what is changed: draught proofing, screening a door, a local heater, a change of clothing or gloves, moving a workstation away from a cold wall, altering the rota. What it produces is a list of controls with names and dates, exactly like any other risk assessment, and the number that matters afterwards is whether the complaints stopped.
Questions people ask about working in cold temperatures the law UK
Can staff refuse to work if it is too cold?
There is no temperature at which a right to stop work arises automatically. What employees can do is raise it as a health and safety concern, through a representative where there is one, and an employer who does nothing about a genuine cold risk is in breach of the duty to assess and control it. In a serious and imminent danger, which extreme cold can become, the general protection against detriment for refusing to work applies. In practice the useful route is the assessment: ask for the cold to be assessed and for the controls to be written down with dates.
Is there a legal maximum working temperature?
No, and for the same reason. The duty is a reasonable temperature and the guidance for heat concentrates on thermal comfort and on the risks of heat stress rather than on a ceiling figure. Where heat is the hazard the controls are the mirror image of the cold ones: shade, ventilation, cooling, water, rest breaks, rotation, and attention to anybody wearing protective equipment that stops them losing heat.
Does the employer have to provide warm clothing?
Where the assessment shows that protection against cold is needed for the work, the clothing is personal protective equipment and the employer provides it and maintains it at no cost to the employee. That includes it being the right size and being replaced when it is worn out, which is where most cold store arrangements actually fail. Ordinary warm clothing for an office that is simply under heated is not personal protective equipment: the answer there is to fix the temperature.