When implementing IAPs, is atmospheric conditions taken into consideration? For example, for any given airport there will be varying atmospheric pressure. This will slightly affect the DH and DA. How might an airport take a wide range of altimeter settings in consideration?
The barometric pressure at the airport doesn't matter as long as you are using that airport's altimeter setting. The altimeter setting is chosen so that it indicates the correct altitude MSL when at field elevation, so regardless of the barometric pressure at field elevation, it will indicate the correct altitude MSL when you are approaching the field.
The temperature can cause additional altimeter errors, however. When it is very cold, the altimeter at field elevation will still indicate field elevation, but the altimeter will indicate that your are higher than you actually are when you are above field elevation. This is why certain instrument approach procedures are not allowed when the outside air temperature is too low, and others require adjustments to the minimums.
The temperature being too high is not a problem from a safety standpoint- the altimeter will indicate lower than it should, but that just means that you are farther from obstacles than you would be on a cooler day.