The 8 Best Heat Stress (WBGT) Monitors

The 8 Best Heat Stress (WBGT) Monitors

The 8 Best Heat Stress (WBGT) Monitors

The 8 Best Heat Stress (WBGT) Monitors

Heat stress (WBGT) monitors are incredibly useful tools to have for monitoring humidity and temperature as part of your heat illness prevention plan.

These devices are generally used in factories, construction sites, and other places prone to high temperatures.

In this article, I’ll share me top choices for the best heat stress monitors, as well as some tips to help you make the right purchase decision.

Kestrel 5400 Heat Stress Tracker

Kestrel 5400 Heat Stress Tracker

  • On-screen warnings when entering danger zones
  • Transparent and instant guidance with regards to illness avoidance measures
  • 15 individual environmental measurements
  • Large backlit display for simple viewing
  • Tracks and documents thousands of data entries with date stamps
  • Data is transferable via USB (the cable is not included)

The Kestrel 5400 is a must-have tool for tracking heat stress conditions and is vital for preventing conditions linked to heat exposure.

This nifty tool is designed with exceptional performance in mind and can be used for various purposes such as construction, military, athletics, industrial hygiene, HAZMAT, and more.

It is a multifunctional device and can perform 15 individual environmental tests, including heat index, WBGT, thermal work limit, barometric pressure, water, and air temperature.

The unit is incredibly user-friendly and has a sizable backlit display for easy reading. The Kestrel 5400 is our top choice in heat stress monitors.

What customers are saying

This unit received only excellent customer reviews. Everyone agrees that this meter is a must-have tool because it presents reliable results every time.

Extech HT30 Heat Stress WBGT Meter

Extech HT30 Heat Stress WBGT Meter

  • Heat stress directory
  • TG (Black Globe Temperature) regulators
  • RH (humidity) and TA (air temperature) readings
  • WBGT values with or without direct UV exposure
  • Automatic power-off function with an override feature
  • RS-232 interface
  • Windows compatibility with optional software

The Extech HT30 Heat Stress Meter is ideal for measuring the influences of humidity, radiant or direct sunlight, and temperature.

It can detect heat stress parameters and has a heat stress directory to assess how warm it will be once the humidity is amalgamated with air movement, radiant heat, and temperature.

The device features TG monitors to evaluate the impact of direct solar radiation on exposed areas, and the WBGT value is displayed regardless of whether there is UV exposure or not.

Other features include its RS-232 interface, on/off automatic power switch, and two AAA batteries.

What customers are saying

The majority of people who bought this model gave it wonderful reviews. They all commended the quality, accuracy, and easy operation of the device.

However, some customers said they had calibration issues.

Kestrel Drop 2 Smart Humidity Data Logger

Kestrel Drop 2 Smart Humidity Data Logger

  • Waterproof
  • Monitors humidity and temperature in dry or wet conditions
  • Can log thousands of data entries
  • Customizable connections, logging rate, and temperature alarms
  • Data can be viewed, saved, or shared from various DROP loggers with a single device (iPad 3rd generation, iOS 6 installed iPhone 4s)
  • Kestrel application supports syncing with iOS or Android devices

This Smart Humidity Data Logger can be used in various applications for measuring humidity and temperature.

It’s a compact handheld tool that can measure and document heat index, humidity dew point, and temperature readings.

It can also sync wirelessly with Android or iOS devices via the Kestrel app. You can save thousands of data entries and have access to months of logging on a single coin-cell battery.

The DROP loggers comply with international and military standards for shock, water, and dust resilience plus the device features a handy D-ring you can use for mounting.

This model is our top choice for the best humidity data logger.

What customers are saying

This device received great reviews. Customers were most happy with the logger’s easy setup, long battery life, accurate readings, durability, and compactness.

Kestrel 3000 Pocket Heat Stress Monitor

If you’re looking for a multifunctional electronic tool that is also portable and can measure dew point, wind speed, humidity, and temperature, look no further.

The Kestrel Pocket Heat Stress Monitor is everything you need. It comes with a wide range of impressive features as well as portability.

It is manufactured in a convenient compact and portable size for you to store in your car, jeans pocket, backpack, and more.

Data can be imported immediately and this nifty device is waterproof and drop-tested, making it the perfect outdoor device.

Sper Datalogging Heat Stress Monitor

The Sper Monitor features OSHA compliant multicolored LCD backlights to differentiate stress alarms and notify workers in the field once dangerous heat levels zones are entered.

With this gadget, you’ll be able to evaluate heat stress figures for both shade and direct sunlight to prevent any heat-related injuries.

The unit comes with 4 x AAA batteries, a built-in tripod screw, transparent instructions, and low-battery alert functionality.

General Tools WBGT8758 Heat Index Monitor

The manufacturer of this device is a pioneer in the industry when it comes to specialized instruments and gadgets that measure WBGT temperature and humidity levels.

Like all their monitors, this one does not disappoint, it has several amazing features and is a portable handheld unit with true heat stress temperature detection and a lightweight design.

With this nifty instrument at your side, you have access to incredibly accurate readings to ensure the safety of your employees all the time. The unit weighs no more than 4.5 ounces.

Extech HeatWatch Humidity & Temperature Stopwatch

This multifunctional temperature and humidity stopwatch can perfectly measure actual temperatures alongside humidity levels to determine the heat levels in specific areas.

Special features include its heat directory measurement, 12 and 24-hour clock, 30 slit/lap memory, stopwatch, and customizable alarm.

Included with your purchase are a battery, user instructions, and a lanyard.

REED Instruments WBGT Heat Stress Meter

This device is a must-have tool for measuring humidity levels, radiant sunlight, and WBGT.

With these measurements, you’ll be able to assess the heat once there is air movement, radiant heat, and the temperature is amalgamated.

You’ll also be able to measure the dew point, barometric pressure, and heat index. The in/out feature shows a WBGT value whether there is direct UV exposure or not.

Employees are vulnerable to strain in environments with high temperatures.

Heat stress monitors are instruments that are used for monitoring temperature, calculating probable heat stroke events, and alerting employees so that they can stop what they’re doing to drink water and cool down.

A heat stress device measures wet bulb globe temperature (WBGT) for both outdoor and indoor areas.

Most heat stress monitors work by measuring the temperature of dry and wet bulbs as well as a black globe to calculate stress in environments with high temperatures.

A WBGT index is a single digit that was taken mathematically from measuring three specific temperatures: wet bulbs, dry bulbs, and globe temperature.

Most people use these devices in outdoor areas but an important thing to keep in mind is that indoor areas are also subject to extreme heat conditions which can result in heat stress.

Heat injuries are probable at WBGT measurements of 75°F and up unless preventative action is taken.

Heat stress monitoring was done by OSHA at various work areas, including:

  • Smelters  – maintenance work and boiler fabrication
  • Mining – hot working environments
  • Food preparation
  • Manufacturing – welding performed in tropical climates inside tanks
  • Electrical distribution – Pole and tower climbing

Small heat stress monitors are also convenient to use in endurance sports, agriculture, military training, foundries, offshore gas, and oil operations.

It should be used in various types of industrial work scenarios as well, specifically in arid and warm tropical environments.


Several WBGT index general guidelines are listed by the US Government Occupational & Environmental Health bulletin, these include:

WBGT index of 78.0 to 81.9°F

Extreme physical exertion might result in a heat stroke or exhaustion. Therefore caution must be practiced.

WBGT index of 82.0 to 84.9°F

Discretion must be used when planning heavyweight exercising for unseasoned workers. This is used as a marginal limit for environmental heat stress sometimes.

WBGT index of 85.0 to 87.9°F

Strenuous workouts like standard cadence or marching must be stopped in unseasoned employees during the initial three weeks of training.

Training exercises can be resumed on a diminished scale after their second training week. Outside activities in the sun must be avoided when exceeding these temperatures.

A WBGT index of 85.0°F or exceeding

Avoid outdoor activities in the sun.

WBGT index of 88.0°F

Strenuous workouts must be reduced for all trainees and recruits that have fewer than twelve weeks of training when in hot temperatures.

WBGT index of 90.0°F

Strenuous workouts and physical training must be halted for everyone.

Not including essential operational responsibilities which are not for training, where the risk of injuries due to heat might be warranted.

Identification & assessment

The identification and handling of heat stress do not merely involve air temperature.

Evaluating the risk of injury or illness due to heat necessitates accurately identifying and evaluating:

  • Work area environments
  • Job requirements
  • Unique employee attributes

Walkthroughs and analysis of the work environment are necessary. Asking workers for information about their problems with heat stress is just as important.

Consider the above and then factor in the area’s history of any heat stress problems, including the time, date, or circumstances in which they happened.