Dynamically changing lightmap intensity?

You can use a post process volume and adjust GI amount in run time via it’s Details panel > Global Illumination > Indirect Lighting Intensity.

Im working on having a world that has dynamic lighting for both day and night, but I want to be able to have nice interior lighting with baked shadows so its not evenly lit.
Im wondering though if its possible to dynamically change the intensity of the lightmaps brightness so at night I can dim the lightmaps and have more natural lighting.

This is what I have during the day

http://i.imgur.com/45wfKXQ.png

But this is what I would like at night.

http://i.imgur.com/v6dnQam.png

Thanks, thats exactly what I needed!