temp = '/Users/lisa/Desktop/GIS/FISH/DATA/01.03.TIFF'
chl = '/Users/lisa/Desktop/GIS/FISH/DATA/01.03CA.TIFF'

lyrt = processing.getObjectFromUri(temp)
lyrc = processing.getObjectFromUri(chl)

entries = []

temp = QgsRasterCalculatorEntry()
chl = QgsRasterCalculatorEntry()

temp.ref = 'lyr@t'
chl.ref = 'lyr@c'

temp.raster = lyrt
chl.raster = lyrc

entries.append( temp )
entries.append( chl )

calc = QgsRasterCalculator( 'lyr@t > 26 AND lyr@t < 30 AND lyr@c > 0.3 AND lyr@c < 2.8', output_path, 'GTiff', lyrt.extent(), lyrt.width(), lyrt.height(), entries )
calc.processCalculation()