OSHA NIOSH Heat Safety Tool

Review by eFreeware

Most weather apps tell you it will be hot. The OSHA-NIOSH Heat Safety Tool, published by the Centers for Disease Control and Prevention, tries to tell you what that heat means for a workday outdoors. It combines the heat index at your location with a risk level and the precautions that OSHA and NIOSH attach to that level, so the number on screen comes with instructions rather than just a temperature.

That framing is what sets it apart. This is not a general forecast app with a heat widget bolted on; it is a tool for planning outdoor work around how hot it will feel hour by hour. If your job, or the job of people you supervise, involves physical effort in the sun, that is the audience this app is built for.

It is free, carries no ads and offers no in-app purchases, and it has been installed more than 100,000 times. The average rating sits at 3.2 from 560 ratings, which suggests a useful tool that has not fully satisfied everyone who tried it.

Turning the heat index into a decision

The core of the app is a visual indicator of the current heat index for your geographical location, paired with the risk level that index corresponds to. Rather than leaving you to interpret a number, it maps the reading onto a category and then supplies precautionary recommendations tied to that category.

That pairing is the part I find most useful in principle. A heat index of a given value means different things depending on how much exertion is involved, and having the risk level and the recommended precautions on the same screen removes a step for anyone who needs to make a quick call about whether to keep working, take more breaks or move a task.

The recommendations come from OSHA and NIOSH, the two bodies whose guidance underpins the app. For a supervisor or a safety officer, that provenance matters: the advice is not the developer's own invention but the published position of the agencies responsible for workplace heat guidance.

Planning the day ahead, hour by hour

The feature that gives the app its planning value is an interactive hourly forecast of heat index values. Each hour comes with its own risk level and its own set of recommendations, so you can look at how conditions will develop across a shift rather than only at the moment you open the app.

I would expect this to be the section people return to. Scheduling a pouring job, a roofing repair or a long stretch of groundskeeping is easier when you can see that the worst of the heat lands in the early afternoon and that the morning hours carry a lower risk level. The forecast turns the app from a thermometer into something closer to a scheduling aid.

Because the hourly view is interactive, you can move through the day and read the guidance attached to each point. That is a more deliberate way of using a weather tool than glancing at a single figure, and it suits the kind of planning that happens the evening before or at the start of a shift.

When the official reading does not match your site

Conditions vary enormously between a weather station and a specific parking lot, warehouse yard or construction site, and the app accounts for that with editable location, temperature and humidity controls. You can adjust the inputs and see how the calculated heat index and its risk level change.

For anyone working in a spot that runs hotter than the surrounding area, this is the difference between generic guidance and something that reflects the actual conditions on site. Entering a measured temperature and humidity gives you a risk level and recommendations based on those figures instead of a regional average.

It also makes the app usable as a what-if tool. Before committing a crew to an afternoon outdoors, you can test a few combinations of temperature and humidity and see where the risk level shifts, which is the sort of check that is hard to do with a standard forecast screen.

Recognizing trouble and responding to it

Alongside the forecasting, the app covers the medical side of heat exposure. It lists the signs and symptoms of heat-related illnesses, naming heat stroke, heat exhaustion, rhabdomyolysis, heat cramps and heat rash, and it provides first aid information for those conditions.

Having that reference in the same place as the risk level and the precautions makes a certain amount of sense. The person checking the heat index before a shift is often the same person who would need to recognize the early signs in a colleague, and first aid guidance that sits one screen away from the forecast is more likely to be consulted than a separate document.

The list is specific rather than vague, covering conditions from cramps and rash through to heat stroke, and the first aid material is attached to each. For a site where a worker suddenly feels unwell, having that information to hand is the practical value here.

What you need before it is useful

The app is a free download with no ads and no in-app purchases, available in the Weather category and rated for Everyone. It was released in May 2017 and last updated in October 2024, when the developer moved it to the new NOAA Weather API service.

The real-time heat index and hourly forecast are tied to where you are. The editable location, temperature and humidity controls exist precisely because the automatic reading may not reflect your actual worksite, and using them well is part of getting a useful answer out of the tool.

You open it, see the current heat index and risk level for your location, and can adjust the inputs or move through the hourly forecast as needed. The learning curve is short because the app's job is narrow: read the conditions, name the risk, give the guidance.

A tool for people who work in the heat

This app is for people whose working day happens outdoors in hot weather: construction crews, agricultural workers, groundskeepers, road maintenance teams, delivery staff and the supervisors and safety officers responsible for them. It is also a reasonable reference for anyone who manages a site and has to decide when conditions warrant changing the plan.

It is not trying to be a general-purpose weather app. There is no extended outlook, no radar, no severe storm tracking and no daily life forecasting; the entire design is oriented around heat exposure at work, with the risk levels and precautions that follow from it. Anyone wanting a broad forecast will find this too narrow, while anyone who needs exactly this will find the focus helpful.

The medical reference section widens the audience slightly. A coach, an event organizer or a volunteer coordinator running an outdoor activity in summer would get something from the symptoms and first aid material, even if the occupational recommendations are aimed at workplaces rather than recreation.

The 3.2 average from 560 ratings is worth weighing. It is not a ringing endorsement, and it points to an app that some users have found less than perfect, though the underlying guidance comes from the two agencies that set the standard for workplace heat safety.

A focused companion for hot-weather workdays

The OSHA-NIOSH Heat Safety Tool does one job and does it in a way that is easy to act on: it takes the heat index at your location, assigns a risk level, and gives you the precautions that OSHA and NIOSH recommend for that level, with an hourly view for planning and manual controls for sites that run hotter than the official reading.

I would recommend it to supervisors, safety officers and outdoor workers who need a quick, authoritative read on heat risk during the working day, and to anyone who wants the symptoms and first aid guidance for heat illness kept somewhere easy to reach. It is free, with no ads and no purchases, which makes trying it a low-stakes decision.

This app concentrates on heat safety for people who work outdoors, and the middling rating suggests it will not please everyone. But as a single-purpose safety reference for people who spend their days in the heat, it covers the ground that matters.

What's new in version 3.5

Uses the new NOAA Weather API Service.