There are 99 weather symbols used in meteorology, to indicate - pictorially - what present weather was occurring at a given weather station, at the time the observation was taken.
For example, the symbol shown at the beginning of the first paragraph on this page means:
"Thunderstorm, heavy, with hail at time of observation."
These weather symbols are plotted immediately to the left of the weather station circle. They are an important part of the significant data reported by the station. All the observed data is tightly plotted on the geographical location of each weather station on a surface analysis map.
The symbols are the "short hand" method used by meteorologists to quickly reveal the "instantaneous" weather story, over a given region, at a given time.
When more than one weather phenomenon is occurring at observation time, only the most significant is reported and, therefore, plotted on the map. For example, if there is haze present, but lightning is visible in the distance with no discernable thunder, then . . .
. . . will be reported and plotted instead of . . .
In the above example, I am sure you will understand that it is more important to report lightning than haze!
Here are 18 of the most common, or generic forms of weather symbols you will find plotted on surface weather analysis maps ... beginning with the most significant!
Funnel cloud(s) or Tornado(s) during the preceding hour or at time of observation.
Thunderstorm, "heavy", with hail at time of observation.
Thunderstorm, slight or moderate lightning activity, - without hail - but with rain and or snow at time of observation.
Thunder heard, but no precipitation at the station.
Shower(s) of hail, with or without rain or rain and snow mixed - not associated with thunder - and of light intensity.
Ice pellets (sleet).
Freezing rain, moderate or heavy (one dot only will mean intensity is light).
Freezing drizzle, moderate or heavy (one "comma" only means light intensity).
Rain shower(s), light in intensity.
Snow shower(s), light in intensity.
Light snow falling (continuous) at time of observation.
Fog, depositing rime ice, or ice fog, sky obscured.
Fog, sky obscured (no appreciable change during the preceding hour).
Heavy blowing snow (generally above eye level). Notice the vertical arrow pointing upward.
Heavy drifting snow (generally below eye level). Notice the vertical arrow pointing downward.
Shower(s) of rain ended in the past hour. NOTE: Any weather symbol with a right bracket, means that the phenomenon ended in the past hour.
Smoke reducing horizontal visibility. Note that "smog" is not reported, as such. When both fog and smoke are present, fog will most likely be reported and plotted on the map … unless smoke is definitely the predominant phenomenon!