Exposure and topography
Actual microclimate depends on slope inclination, slope exposure to the sun and vegetation cover. These three elements together can create climatic differences within a few meters of alpine terrain which meteorological stations would only measure across 1-2 km of elevational gradients.
Above the alpine treeline, microclimate depends more on relief and exposure than on macroclimate.

1 -
The annual course of root zone temperature (10 cm below the surface) at
exactly 2500 m altitude, but at sites contrasting in slope exposure (near
Furka Pass, Swiss Alps, c. 300 m above the climatic treeline).
(Körner 2003)

12 -
Extreme microclimate contrasts across very short distances.