No matter how good your local weather service, there is no substitute for good outdoor thermometers, or maybe even for three or four of them. Even a small city lot, patio or porch will have microclimates. Accurate temperature measurement will help you plan gardening, outdoor recreation areas and more.
Outdoor Thermometers can be simple or they can be decorative. They can be dials, or they can be, well, a traditionally shaped thermometer. They can have simple or highly ornamental backgrounds.
What Do Thermometers Measure and How Are They Marked?
Thermometers measure heat, but they can be marked in different kinds of measurements. The three most common thermal measurement types are Fahrenheit, Celsius, and Kelvin.
It is important to know how your thermometer is marked. The easiest way to explain this importance is to discuss the temperature at which water freezes. The freezing temperature for Fahrenheit is 32 degrees; the freezing temperature for Celsius is 0 degrees.
Kelvin, which is primarily used in scientific situations, is a little different. Zero degrees Kelvin is absolute zero, or -273.15 degrees Celsius. Fortunately, you won’t usually need Kelvin marked on your outdoor thermometer.
What Are the Types of Thermometers?
Depending on where you live, the common thermometer marking might be in Fahrenheit or in Celsius. Some thermometers will be marked in both, so it is a good idea to know which is which.
- Liquid Outdoor Thermometers
In times past, thermometers contained mercury. When one of them broke, little globules of mercury could spill out. But as mercury’s toxicity has become better understood, mercury thermometers have become illegal in many places. Liquid thermometers today contain non-toxic alcohol. Like the mercury thermometers, as the liquid becomes warmer, it expands, moving up the containing column to show the temperature.
Liquid thermometers that are marked in both Fahrenheit and Celsius usually have a scale on either side of the glass tube that houses the measuring liquid.
- Dial Outdoor Thermometers
Dial thermometers are easy to read. Like the liquid thermometers, they are often marked in both Fahrenheit and Celsius. Again, look at your thermometer carefully so that you know which is which. For example, one lovely brass thermometer has Fahrenheit marked as the outer ring of numbers, and Celsius as the inner ring. When you know which is which, it can help you to understand the relationship between the two.
Another thing to know about dial thermometers is that they operate through the use of a bimetal spring. Two different kinds of metal are welded together. These metals will expand or contract at different temperatures. This expansion or contraction will cause the metal to stretch out or to retract, and this action will change the location of the pointer on the dial.
Basic dial thermometers might have large numbers, making them easy to read. They can, however, have beautiful background scenes painted behind the numbers. Some will have only one measuring system, while others will have both Fahrenheit and Celsius marked.
Although these are usually indoor thermometers, you could set one of these up in a garden or on your patio if you do not anticipate freezing temperatures. These beautiful, interesting thermometers are filled with water. The temperature is indicated by colored balls that rise or fall depending upon the warmth of the water.
- Weather Centers and Decorative Displays
Some outdoor thermometers are set up as part of a weather center that might include barometric readings, along with humidity and wind direction. It might even have a rain gauge attached to it to help complete your understanding of the world around you.
Stylized sun and moon displays are a frequent theme for outdoor weather centers. This should not be too surprising since the sun and moon phases are certainly part of our natural world.
- Outdoor Sensors/Indoor Displays
Digital thermometers can be extra sensitive to temperatures, so it is not uncommon for them to have an outdoor sensor that leads to an indoor display. They can usually be set to display either Fahrenheit or Celsius.
The outside sensor is often unobtrusive, while the indoor display often has a sleek, modern appearance. Sometimes these sensors can be attached to a unit that will send the readings to your phone or computer, which can be handy if you are monitoring your home remotely.
Different models of digital outdoor thermometer offer a wide variety of functions. Some of the essential features to look for in your outdoor thermometer include:
Temperature accuracy may not be at the top of your list of features if you just want to know what to wear, however, for people who rely on temperature measurements for controlling the ambient temperature in greenhouses or food storage areas, precision is an important issue. Look for digital thermometers with an accuracy range of at least ±0.4F.
If you are looking for an easy to read digital thermometer that can be seen from the warmth and safety of your home, you need a unit with a large, clear display.
Avoid displays with too much information cluttering the screen. Opt for an outdoor thermometer will a scrolling function that has the temperature as the primary display mode but also allows you to access information on humidity, barometric pressure, and other weather conditions as necessary.
A backlight display also allows you to see vital information on your outdoor thermometer, especially in low light conditions. Blue or white LED backlights create a high contrast between the digital reading and the rest of the screen for better visibility.
Avoid the need for constant calibration with an easy-to-program unit that allows you to set a high/low-temperature alarm and gather information on a variety of weather conditions.
Long Battery Life
Wireless capability allows for greater flexibility when gathering weather data. However, to ensure consistently accurate readings, make sure your outdoor thermometer and sensor have long battery life. Look for units with a minimum battery life of at least 12 months.
Wide Transmission Range
The sensors collect weather data and transmit it back to a central unit in your home. The most accurate and informative models have a wide transmission range allowing you to use the thermometer for a more versatile variety of applications. The best digital outdoor thermometers have a transmission range between 200-500 feet from the central unit location.
For most people using a digital outdoor thermometer, the temperature isn’t the only measurement they are seeking. Look for a multifunctional thermometer that accurately measures humidity and barometric pressure to make weather forecasts, moon phases for tidal predictions, and wind speed.
Outdoor thermometers can be fun and informative. They can be utilitarian in appearance, or they can be elaborately beautiful. Thermometers can be a stand-alone item or part of your home weather station. Some of them can even send information to your computer or phone. Liquid-in-glass and digital thermometers give the most accurate readings.