What is the typical water pressure for a sprinkler system outside a home?
Not clear what the reason for the question is. However, nominal water pressure for most residential homes is in the range of 40-70 psi (pounds per square inch). It can vary due to the distance from the home to the water source (such as a water tower), how much water is being used by surrounding homes (higher usage will lower the pressure), the capacity of the water company to maintain pressure as usage varies, etc. Most heating systems and water heaters require pressure reducing valves in order to make sure that the water pressure into those systems does not get too high which can cause damage. In special situations, where the home is far from the water source and/or on high ground, a water pump may be necessary to maintain a reasonable pressure. Getting back to your question, are you talking about a sprinkler system for watering a lawn or a sprinkler systems for putting out a fire. In any case, both systems will have minimum pressure requirements based on how many sprinkler heads are in the system. Too many heads would prevent either type of system from working properly.
For yard sprinklers (irrigation) this is usually figured the other way around. Find out what your water supply is capable of, then build a system which will work well within that. If you have an existing system and you're trying to find an estimate without measuring... every system is different. There's not a standard pressure.
To find our what your supply pressure is, there are methods of measuring and calculating, or you can call your water supplier and see if they know (frequently they have nearby pressure measures for fire hydrants).
The end result is typically somewhere between 40-60 PSI. If it gets much above 60, you may need a pressure regulator for your yard (I needed one for my install this spring) which will typically bring the pressure down to 60. If sprinkler pressure is much higher than that, it can cause shudder in the pipes which can weaken them over time. Too low may involve pumps to fix, I'm not familiar.
If you are asking about landscape irrigation, two important pieces of data are water pressure and flow rate. Although many parts of a system can operate over a wide range of water pressures, the nozzles are designed for and perform best around 30 or 40 PSI. The problem with low pressure is obvious but excessive high pressure can cause misting and otherwise waste water and shorten the life of the system.
A pressure regulator is a good solution for high pressure but note the maximum flow rate and check for compatibility. For example, I have one in my system with a max of 480 gallons per hour or 8 gallons per minute.
Note that even if the static water pressure is sufficient, overloading your water supply with a higher flow rate than it can support will cause the water pressure to drop. It is important to maintain the desired pressure at the operating flow rate for proper coverage. However, it is the static water pressure that affects the life of your valves and pipes.
Rainbird is one of many companies that provides copious free information on their web site.
If you are designing a new system, you should look into the MultiStream MultiTrajectory Rotors (MSMTR) as they perform better than conventional nozzles. Both Rainbird and Hunter have these products.