Is there any relation with the temperature of the air or is it just a standard procedure?
Red/blue for pressure is in no relation to surface temperature. Storms develop where the pressure is very low. Red being associated with danger is a good color choice for low pressure.
Storms are created when a center of low pressure develops with a system of high pressure surrounding it.
Low pressure is also associated with decreased aircraft performance, both lift and engine power. See below and find the strongest storm system.
Blue for cold and red for hot is used for coloring the weather fronts:
(Source) 1. cold front 2. warm front 3. stationary front.
The red color is universally associated with evil, suffering, blood, fire...
Low pressures are associated with rain, storms, even with hurricanes and tornados... High pressures are associated with stable weather, sun, blue skies, absence of wind... Hence, it's no wonder that low pressure is indicated in red, and high pressure in blue...
Socialist-minded people do strongly object... For them, the red color is a symbol of revolutionary progress...
"From high to low, look out below." Pilots use this mnemonic to remember that when flying from high pressure into low pressure, the altimeter will read higher than actual altitude, which can be dangerous. (also true from high temperature into low temperature).
I don't know if it was by design, but I've always associated the red low pressure with danger, because flying from an area of high pressure into an area of low pressure can result in flying lower than indicated on the altimeter and also, low pressure is usually associated with less than desirable flying weather. Additionally, high pressure is often associated with blue skies. So maybe that is the rationale, if there even is one.
The colors of high and low pressure areas are chosen to represent what occurs aloft, not at the surface. Lows are composed of warm rising air; highs of cold sinking air. That's why highs are represented by blue, which equates to cold air, and lows are represented by red, which equates to warm air. Again, this is aloft, near the top of the troposphere, not at the surface. This website explains the sinking and rising aspects of highs and lows.