Hi!
This look like a Nitrogen deficiency (older/lower leaves going yellow), but it's may be the result of other parameters. Senescence is improbable after only 6 weeks of flowering, or maybe this strain is fast (check the trichomes).
For your high temperatures issue, you must try Elycitor from Bio Technology. It's basically a mix of bacteria, but my room goes up to 34°C last summer and that didn't bother any of the 4 plants in it. ^^