Temperature is a degree of hotness or coldness the can be measured using a thermometer. It's also a measure of how fast the atoms and molecules of a substance are moving. Temperature is measured in degrees on the Fahrenheit scale.

The Heat Index uses the temperature and the relative humidity to determine how hot the air actually "feels." When humidity is low, the apparent temperature will be lower than the air temperature, since perspiration evaporates rapidly to cool the body. However, when humidity is high (i.e., the air is saturated with water vapor) the apparent temperature "feels" higher than the actual air temperature, because perspiration evaporates more slowly.

Wind is air in motion. It is produced by the uneven heating of the earth’s surface by the sun. Since the earth’s surface is made of various land and water formations, it absorbs the sun’s radiation unevenly. Two factors are necessary to specify wind: speed and direction.

The Average Wind Speed is calculated by aggregating the last 10 minutes of statistics, plus the statistics for the current minute. For example, the two minute high wind speed is the highest value recorded in the last two full minutes plus the current minute divided by the number of samples over the same period.

Wind Chill takes into account how the speed of the wind affects our perception of air temperature. Your body warms the surrounding air molecules by transferring heat from your skin. If there’s no air movement, this insulating layer of warm air molecules stays next to your body and offers some protection from cooler air molecules. Wind disperses this layer of warm air, causing the air temperature to "feel" colder. The faster the wind blows, the quicker the layer of warm air is dispersed, and the colder you feel. Above 93.2ºF, wind movement has no effect on the apparent temperature.

Humidity refers to the amount of moisture in the air. The relative humidity tells how much water the air is holding compared to how much it could hold at a certain temperature. If our blob of air has a relative humidity of 50% then that means it is holding half of the amount of water a blob of air 80ºF could hold. The relative humidity can change if the moisture changes or if the temperature changes.

The THW Index uses humidity, temperature and wind to calculate an apparent temperature that incorporates the cooling effects of wind on our perception of temperature.

The THSW Index uses humidity, temperature, the cooling effects of wind and the heating effects of direct solar radiation to calculate an apparent temperature.

Dew Point is the temperature to which air must be cooled for saturation (100% relative humidity) to occur, providing there is no change in water content. The dew-point is an important measurement used to predict the formation of dew, frost, and fog. If dew-point and temperature are close together in the late after noon when the air begins to turn colder, fog is likely during the night. Dew-point is also a good indicator of the air’s actual water vapor content, unlike relative humidity, which takes the air’s temperature into account. High dew-point indicates high vapor content; low dew-point indicates low vapor content. In addition a high dew-point indicates a better chance of rain and severe thunder storms. You can even use dew-point to predict the minimum overnight temperature. Provided no new fronts are expected overnight and the afternoon Relative Humidity ³ 50%, the afternoon’s dew-point gives you an idea of what minimum temperature to expect overnight, since the air is not likely to get colder than the dew-point anytime during the night.

Barometric Pressure is the weight of the air that makes up our atmosphere exerts a pressure on the surface of the earth. This pressure is known as atmospheric pressure. Generally, the more air above an area, the higher the atmospheric pressure. This, in turn, means that atmospheric pressure changes with altitude. For example, atmospheric pressure is greater at sea-level than on a mountaintop. To compensate for this difference in pressure at different elevations, and to facilitate comparison between locations with different altitudes, meteorologists adjust atmospheric pressure so that it reflects what the pressure would be if measured at sea-level. This adjusted pressure is known as barometric pressure.

Barometric pressure changes with local weather conditions, making barometric pressure an important and useful weather forecasting tool. High pressure zones are generally associated with fair weather, while low pressure zones are generally associated with poor weather. For forecasting purposes, the absolute barometric pressure value is generally less important than the change in barometric pressure. In general, rising pressure indicates improving weather conditions, while falling pressure indicates deteriorating weather conditions.

The Barometric Trend shows the direction of change (higher, lower, steady) of the barometric pressure over the last three hours.

Ultraviolet Index: Energy from the sun reaches the earth as visible, infrared, and ultraviolet (UV) rays. Exposure to UV rays can cause numerous health problems, such as sun burn, skin cancer, skin aging, and cataracts, and can suppress the immune system.

The UV Index measures the intensity of UV. It was first defined by Environment Canada and since has been adopted by the World Meteorological Organization. UV Index uses a scale of 0 to 16 to rate the current intensity of UV.

Index Value / Exposure Value
0-2 / Minimal
3-4 / Low
5-6 / Moderate
7-9 / High
10+ / Very High

Solar Radiation What we call "current solar radiation" is technically known as Global Solar Radiation, a measure of the intensity of the sun’s radiation reaching a horizontal surface. This irradiance includes both the direct component from the sun and the reflected component from the rest of the sky. The solar radiation reading gives a measure of the amount of solar radiation hitting the solar radiation sensor at any given time, expressed in Watts per square meter (W/m2).

Evapotranspiration (ET) is the combination of water that is lost from the soil through evaporation and through transpiration from plants as a part of their metabolic processes.

Snowfall is the process of precipitating snow and is a type of precipitation in the form of crystalline water ice, consisting of a multitude of snowflakes that fall from clouds. Since snow is composed of small ice particles, it is a granular material. It has an open and therefore soft structure, unless packed by external pressure. Snowflakes come in a variety of sizes and shapes. Snowfall amount, and its related liquid equivalent precipitation amount, are determined using a variety of different rain gauges.

Precipitation is any product of the condensation of atmospheric water vapor that is deposited on the earth's surface. It occurs when the atmosphere becomes saturated with water vapour and the water condenses and falls. This shows the amount of precipitation in increments of .01 inches that has accumulated within the last 24 hours.