How long does a temperature mapping study take?

WHO guidance says at least seven consecutive days for a store, including five working days and two weekend days, so both busy and quiet periods are captured. Cold rooms can be mapped in 24 to 72 hours.

How often should a warehouse be temperature mapped?

WHO gives every three years as an example, plus after any significant change to the store. EU GDP ties the repeat to a risk assessment or significant modifications. Stores affected by the weather are mapped in both the warmest and the coldest season.

What is the difference between temperature mapping and temperature monitoring?

Mapping is a study: many loggers, for a set period, to find the hot and cold spots. Monitoring is permanent: devices placed where the mapping found the extremes, recording every day the store is in use.

Term

Temperature mapping

Temperature mapping is the documented measurement of how temperature, and often humidity, varies across a storage area, to find its hot and cold spots before goods are stored. EU Good Distribution Practice for medicines calls for an initial mapping under representative conditions before use; WHO guidance sets how loggers are spaced, how long it runs and when to repeat it.

Also called warehouse temperature mapping, thermal mapping, temperature mapping study, cold room mapping, mapping studyUpdated 13 October 2026

How a study is set up

Choice	WHO guidance
Grid	A logger every 5–10 m; up to 20–30 m in very large facilities
Heights	Several levels — in a 6 m store, 0.3, 1.8, 3.6 and 5.4 m
Duration	At least seven consecutive days, five working and two weekend; 24–72 hours for cold rooms
Logging interval	One reading every 1 to 15 minutes
Seasons	Once in the warmest season and once in the coldest; not needed for cold and freezer rooms
Repeat	Periodically — every three years, for example — and whenever the store is significantly modified

WHO Technical Report Series 961, Supplement 8, May 2015

Worked example: how many loggers

40 m × 30 m store on a 10 m grid → 5 × 4 = 20 grid points · × 4 heights (0.3, 1.8, 3.6, 5.4 m) = 80 loggers · 7 days at one reading every 15 minutes → 672 readings per logger, 53,760 in all

Spacing, heights and duration follow WHO's 2015 supplement; the store is illustrative. WHO gives spacing rather than a count, so the count follows from the grid.

What the results are for

Mapping should define the zones that must not hold temperature-sensitive products, WHO says, and EU GDP asks for the permanent monitoring devices to sit in the areas that experience the extremes of fluctuations. So the map decides two things: which racks — by a dock door, under a roof — are off-limits for product kept at, say, WHO's refrigerated 5 ± 3 °C, and where the everyday monitors go.

Who requires it

In the EU, the 2013 GDP guidelines call for an initial mapping before use and a repeat according to a risk assessment or after significant modifications, and each wholesale distributor must designate a responsible person. In the US, 21 CFR 205.50 asks prescription drug distributors for temperature and humidity recording equipment, devices or logs, without naming mapping. Oman's Ministry of Health made mapping explicit for warehouses, storage rooms and refrigerators in August 2026; India's CDSCO guidance on it is still a draft.

The mistake people make

Starting the loggers at different times. WHO calls a common start time essential, because otherwise the readings cannot be time-correlated and a hot spot at 14:00 on one logger can't be set against its neighbours. The other is mapping once, in a mild month: a store mapped only in spring has not been mapped for summer.

FAQ