I can't find much of any rules for sleep in pathfinder, or at least the requirement for sleep. Specifically, what happens if you sleep with no bed (in the wilderness, etc)? What happens if you sleep in inclement weather? What happens if you don't sleep at all? Are there rules for these situations, and if not, does anyone have house rules for it that they like?
The d20PFSRD collates the relevant bits conveniently for you here.
Optional but RAW:
You might also consider using a variant rule where characters who do not get a full night’s sleep may suffer the effects of fatigue. If a PC does not get at least 6 hours of sleep, she must make a DC 15 Fortitude save or be fatigued and take a –1 penalty on all other checks and saving throws against sleep effects. A second night without sleep requires another DC 15 Fortitude save. A failed save results in the character becoming exhausted and the penalties increasing to –2. A third failed save on the next night increases the penalties to –3.
and from the Armor Check Penalty section:
A creature that rests or sleeps in medium or heavier armor gains the fatigued condition if they do not possess either the Endurance feat or some other class or race ability which allows them to sleep in such uncomfortable gear.
As for inclement weather and the like, the weather section doesn't have instructions on how much it disrupts sleep but I'd think that anything that overcomes your +10 Perception DC when asleep would wake you up.
The fatigued and exhausted conditions are removed by rest so not resting/sleeping while having one of those conditions means you retain them.
And while not explicitly stated sleeping in inclement weather might be ruled as not being restful enough.
For Wizards each interruption of their sleep adds 1h to the time they need to rest:
Rest: To prepare his daily spells, a wizard must first sleep for 8 hours. The wizard does not have to slumber for every minute of the time, but he must refrain from movement, combat, spellcasting, skill use, conversation, or any other fairly demanding physical or mental task during the rest period. If his rest is interrupted, each interruption adds 1 hour to the total amount of time he has to rest in order to clear his mind, and he must have at least 1 hour of uninterrupted rest immediately prior to preparing his spells. If the character does not need to sleep for some reason, he still must have 8 hours of restful calm before preparing any spells.
Not directly about sleep but Wizards (and possibly other prepared casters) have a problem with inclement weather:
Preparation Environment: To prepare any spell, a wizard must have enough peace, quiet, and comfort to allow for proper concentration. The wizard's surroundings need not be luxurious, but they must be free from distractions. Exposure to inclement weather prevents the necessary concentration, as does any injury or failed saving throw the character might experience while studying. Wizards also must have access to their spellbooks to study from and sufficient light to read them. There is one major exception: a wizard can prepare a read magic spell even without a spellbook.
Spell Selection and Preparation: A divine spellcaster selects and prepares spells ahead of time through prayer and meditation at a particular time of day. The time required to prepare spells is the same as it is for a wizard (1 hour), as is the requirement for a relatively peaceful environment.
Houserule: being wet or otherwise handicapped influences the temperature when it comes to using the cold dangers rules. For being outside while it is raining at 50°F is as likely to harm you as it is at 40°F when it is dry.