It turned cool last weekend, and the week has been insane for us. I haven't been sleeping well due to a finger injury, so it's been rough. We swam Monday, but the cover hasn't been off the pool since then. Lows have been in the 50s and highs 78-81. I was concerned that the swimming season was over. Went out after work tonight thinking I should at least roll the cover up to let some sunlight hit the water. 96 degrees I'd never have believed it could have been so warm even if it had been hot this week. It's like swimming in a hot tub. I only have 6 4X8 panels for 192sq-ft, which is quite a bit less than the recommended amount for my pool, but it has apparently been doing the job.