At Low Fluid Temperature

WARNING: This page is about a different car, the 2003 Infiniti I35. However, it is still accessible from the selected car via links, so may be relevant.

Fluid viscosity and frictional characteristics of the clutch facing change with fluid temperature. Clutch engaging or band-contacting pressure is compensated for, according to fluid temperature, to stabilize shifting quality.
The line pressure is reduced below 60°C (140°F) to prevent shifting shock due to low viscosity of automatic transmission fluid when temperature is low.

Fig 1: Line Pressure And Throttle Opening Normal Control Graph
Courtesy of NISSAN MOTOR CO., U.S.A.
Line pressure is increased to a maximum irrespective of the throttle opening when fluid temperature drops to - 10°C (14°F). This pressure rise is adopted to prevent a delay in clutch and brake operation due to extreme drop of fluid viscosity at low temperature.

Fig 2: Line Pressure And Throttle Opening Normal Control Graph
Courtesy of NISSAN MOTOR CO., U.S.A.