First, the only areas that will be audited are the ones where 17025 accredited calibration or testing takes place.
In those areas you will need to document (they will ask for the document) the environmental conditions required to be suitable for laboratory activities. That will include temperature and humidity, but can include anything that can influence your results, such as vibration, dust, or electrical supply quality.
The lab shall "monitor, control, and record environmental conditions". You need to be able to produce records that show that the conditions are within the controls you have established (and what happens if they drift out of control), this will be true for all areas where 17025 activities are conducted.
You can probably get away with thermohygrometers and showing that you are recording the data on your records, but be prepared to prove that those areas have been kept in control. That's why most labs have recorders in each area, so they can produce the history.