Weather sense (1, WIS, +1): This proficiency enables a character to determine
something about what the weather conditions will be in the
place he is currently occupying during the coming six hours. A
successful Proficiency Check indicates that the character correctly
ascertains at least one general fact about the upcoming
conditions: rain is on the way, rain is not on the way, it will get
warmer, it will get cooler, conditions will remain basically the
same, and so forth. The Dungeon Master always rolls Proficiency
Checks for weather sense, and is not obliged to reveal the result
of the attempt. The information gained from a successful check is
whatever the Dungeon Master deems it appropriate for the character
to know (and, of course, the information must be at least
generally true). A failed check indicates that no definite information
is gained, or (at the Dungeon Master’s discretion) some incorrect
information is obtained.
This proficiency can only be used without penalty once in every
24-hour period. For every attempt beyond the first one on a given
day, the Dungeon Master will attach a cumulative +2 modifier to
the die roll (decreasing the chance that multiple Proficiency
Checks during a single day will all succeed). Also, when a
weather sense Proficiency Check is failed, any subsequent
check in the next 12 hours will automatically fail.
Sometimes, impending weather is so obvious that even a character
without this proficiency will be able to tell what is going to
happen. In such cases, the Dungeon Master should not require,
or even acknowledge, an attempt for a Proficiency Check and
should instead simply describe the conditions, which would be
apparent to anyone who can see. For instance, anyone ought to
know that “a mass of dark clouds on the horizon, moving toward you” is a pretty clear sign that a rainstorm is on the way.