Can anyone recommend a 12 VDC power supply that can operate in either outdoor temperatures (maybe -24 through 44 degree Celsius) and/or attic temperatures (temperatures may be in excess of 66 degrees Fahrenheit)? The source of power would be 110 volts and would use less than 1.5 amps to power a 12 volt siren and/or light.
Your temperature range requirements may not be necessary if you can provide power for the light and siren from within your house, rather than the attic (seems doable from your post).