The combined effects of precipitation (or dust) and wind that accompany all storms reduce visibility ranges by three-quarters, imposing a –8 penalty on Perception checks.Areas of darkness include an unlit dungeon chamber, most caverns, and outside on a cloudy, moonless night.
Characters with low-light vision (elves, gnomes, and half-elves) can see objects twice as far away as the given radius. Double the effective radius of bright light, normal light, and dim light for such characters.
Characters with darkvision (dwarves and half-orcs) can see lit areas normally as well as dark areas within 60 feet. A creature can't hide within 60 feet of a character with darkvision unless it is invisible or has cover.
Perception Modifiers DC Modifier
Distance to the source, object, or creature: +1 DC/10 feet
At most, a PC can identify things within a total distance equal to (20+her bonus on perception checks) x 10 feet.
So a first level elf ranger might have low-light vision and a +8 bonus (1 rank + 3 trained + 2 racial + 2 wisdom), for a total distance of 280 feet ([1d20+8]*10).
However, a storm (-75% distance) knocks that down to 70 feet.
And since it is at night (storm clouds reduce light levels to "darkness"), he gets no benefit from his low-light vision.
A character with darkvision has a stated maximum sight distance (i.e. 60 feet). In the same night time storm, that also gets knocked down 75% to a mere 15' of darkvision (her normal vision likely sees further).
If the DM set this storm on the night of a full moon, he may adjucate that the light level is dim, and reduce the penalty for low-light vision characters by half (since they can see "twice as far"), giving the elf a maximum distance of 140 feet.