The ideal storage temperature is 55 to 100 degrees.  It can freeze and will thaw with no harm.  You will notice the surfactants will solidify and separate at 40 degrees and below.  If that occurs, the solution will need to be warmed to typical room temperatures.  Once warmed, shake slightly to remix.  Product should not lose any effectiveness.  Higher temperatures will start killing off the live enzymes making it less effective when reaching over 150 degrees.