temp should not affect the results of FW tests. the only real temp related test is salinity, and only if you're using a hygrometer, and only if that hydrometer isn't calibrated for SW tank temperatures (laboratory hydrometers are calibrated to around 60F, which requires altering the test results of 80F water by 0.002SG...but I digress).
warmer water holds less oxygen, and makes ammonia more toxic...but the test results for oxygen and ammonia will still be as accurate as a hobby grade test kit can be.