We all consult our local weather forecast on a daily basis and have done so since memory serves. But when it comes down to it, do we fully understand what the information that's presented to us means? Here's an easy-to-digest explanation of what the basic weather elements included in your daily forecast -- including air temperature, air pressure, chance of rain, sky conditions, dewpoint temperature, humidity, and wind -- are telling you.
1. Air Temperatures
When someone asks what the weather is like outside, air temperature is often the first condition we describe. Two temperatures -- a daytime high and a nighttime low -- are always given for a 24-hour calendar day full day's forecast.
Knowing what time of day the max and min temperatures are reached is just as important as knowing what they will be. As a rule of thumb, you should expect the high to happen near 3 or 4 o'clock pm local time, and the low, near sunrise of the following day.
2. Probability of Precipitation (Chance of Rain)
Next to temperature, precipitation is the weather condition we want to know most. But what exactly does the phrase “chance of precipitation” mean? The chance of precipitation tells you the likelihood (expressed as a percentage) a location within your forecast area will see measurable precipitation (at least 0.01 inch) during a specified time period.
3. Sky Conditions (Cloudiness)
Sky conditions, or cloud cover, tells you how clear or cloudy the sky overhead will be throughout the day's entirety. While this may seem a frivolous weather observation, clouds (or a lack thereof) influence air temperature. They determine how much of the sun's energy reaches the Earth's surface to heat it during the day, and how much of this heat that was absorbed gets released from the surface back out into space at night. For example, thick stratus clouds block sunrays, while wispy cirrus clouds allow heat to penetrate and warm the atmosphere.
Wind measurements always include the speed and direction of where winds are blowing from. Sometimes your forecast won't mention wind speed outright, but will use descriptive words to suggest it. Whenever you see or hear these terms, here's how to interpret how fast that is:
|Forecast Terminology of Wind Intensity||Wind Speed|
|Light/Variable||5 mph or less|
|Breezy (if mild weather). Brisk (if cold weather)||15-25 mph|
Guilty of never paying much attention to air pressure? Well, you should! It's an easy way to assess whether the weather is settling down or storms are brewing. If pressure is increasing or is over 1031 millibars (30.00 inches of mercury) it means weather is settling, whereas pressure that's falling or is near 1000 millibars means rain may be approaching.
Although it resembles your air temperature, dewpoint temperature isn't a "regular" temperature that tells how warm or cool air feels. Rather, it tells what temperature air needs to be cooled to in order for it to become saturated. (Saturation = precipitation or condensation of some sort.) There are two things to keep in mind about dewpoint:
- It will always be lower than or equal to the current air temperature -- never higher than it.
- If it equals the current air temperature, it means that the air is saturated and humidity is 100% (that is, the air is saturated).
Relative humidity is an important weather variable because it tells how likely precipitation, dew, or fog is to happen. (The closer RH is to 100%, the more likely precipitation is.) Humidity is also responsible for everyone's discomfort during hot weather, thanks to it's ability to make air temperatures "feel" much hotter than they actually are.