Interestingly enough, the FAA needed to put out guidance on this issue you are trying to get to the bottom of.
Here is the scenario. You are flying on a fixed glidepath to the runway. You are exactly in the middle of the localizer and glideslope signal. To put things into perspective, these signals do not change with atmospheric conditions. A glideslope bean will put the aircraft at the same true altitude every single day.
On ILS approaches with quite a few stepdown procedures, the requirements is to remain at or above the MEA for each segment until the final approach fix at which time you will descend on the glideslope to the runway.
Quite a few pilots will capture this glideslope at an altitude higher that what the published altitude is at the final approach fix.
Here is the jist of the InFo from the FAA. In cold than normal weather, those pilots who capture the glideslope high will most likely remain at or above the MEAs for those intermediate segments. IAF --> stepdown --> stepdown --> PFAF.
In warmer than normal weather, the same pilot will most likely descend below the MEA for those segments and could cause traffic issues for other aircraft.
The saying "FROM HIGH TO LOW... LOOK OUT BELOW" is true for both pressure and temperature.
The METAR for the airport will automatically compensate for the temperature differences through its use of the altimeter setting. Remember, the altimeter setting is representing the altitude you would be at above sea level.
A really good example of this is in Colorado. Today, the METARS look like this.
Wilkerson Pass (Elev. 11,259 FT) - K4BM 132135Z AUTO 17005KT 10SM SCT032 SCT038 BKN120 12/05 A3077 RMK AO2 LTG DSNT NE
Red Cliff Pass (Elev. 12,047 FT) - KCCU 132135Z AUTO 11013KT 10SM SCT037 SCT055 BKN080 18/04 A3078 RMK AO2
La Veta Pass (Elev. 10,124 FT) - KVTP 132135Z AUTO 10010G14KT 10SM SCT025 SCT034 SCT039 17/08 A3064 RMK AO2
Alamosa Airport (Elev. 7,542 FT) - KALS 132152Z AUTO 11013G25KT 10SM CLR 28/06 A3038 RMK AO2 PK WND 11027/2126 SLP182 T02830061
Colorado Springs Airport (Elev. 6,187 FT) - KCOS 132054Z 14011G18KT 10SM SCT070 SCT250 28/08 A3038 RMK AO2 SLP195 T02830083 56009
Gunnison Airport (Elev. 7,667 FT)- KGUC 132127Z AUTO 08016KT 10SM -RA SCT080 OVC100 22/08 A3042 RMK AO2 PK WND 12029/2105 LTG DSNT E AND SE TSE16RAB24 PRESRR P0000
I have tried to show passes and airport close to each other to preclude the possibility or an airmass or pressure change.
Look at those altimeter settings. They are corrected for the non-standard temperatures to show true altitude at their locations. The altimeter setting must be higher in the passes because it is warmer than standard today in Colorado. If you look at these airports in the winter, you may find the altimeter settings are lower than the corresponding airports.
The elevations listed are for the weather station and not the airport elevation as found in the chart supplements.