It's not really the values, but the trend. The value may slightly shift. I'd say that you ovulated around day 17 or are getting ready to. Track over a couple of months and you will see the trend. If you get your period this month, the temp will go down the lower range that you track at. This is the normal trend. 35 (ish) all the way until you ovulate. Then 36 (ish) (your temp is high 35 and low 36 so you'd look for high 36 and low 37 after ovulation). Once you ovulate, you are the higher temp. That lasts until your period comes and THEN it drops back to the high 35/ low 36 range again. So, you aren't really able to see your period coming from what is happening now and it's more an indication that you have or are about to ovulate. Which makes sense as most women ovulate around day 14 to 15 (and a few days after would not be unusual depending on how long your cycle is).