When Should I Mark a Temperature Shift in the App?


It seems there’s a bit of confusion out there about what exactly the temperature shift is and when to mark a temperature shift in the app. So in this post, I’m going to do my best to lay it out as clearly as possible.

First, to catch the temperature shift, you’ll need to track your basal body temperatures – i.e., your temperature taken each morning first thing when you wake up, before getting out of bed.

Before you ovulate, your basal body temperatures will be in a lower, pre-ovulatory range. For most women this is around 97.0-97.7 F/ 36.11-36.50 C, but if your temperatures are slightly lower or higher than that, that’s perfectly normal.

The day after you ovulate, your basal temperature will rise, and it should stay in a higher range for the rest of your cycle (typically 97.7-98.3 F/ 36.50-36.83 C for most women, but again, if your temperatures are slightly outside of that range, it’s fine). The day of the rise from the lower to the higher range is the day of the temperature shift.

In order to classify as a true temperature shift, your temperatures must meet these 3 requirements:

1) Your temperature on the day of your temperature shift must be at least .2 degrees F/.11 degrees C above your temperature from the previous day.

2) Your temperature on the day of your shift must be at least .1 degrees F/.05 degrees C above any of your temps from the previous six days.

3) Your temperatures must stay at least .1 degrees F/.05 degrees C above the 6 temps prior to the shift for at least 3 consecutive days in order to confirm that ovulation occurred.

So, if your temperature goes up one day and then goes back down the next, it’s not a temperature shift. Remember that a lot of factors can cause your temperature to be higher than normal on any given day, such as stress, illness, restless sleep, moving around before taking your temperature, waking up later than normal, or drinking alcohol the night before. 

This chart shows a clear temperature shift on Cycle Day 14 (March 23).

This chart shows a clear temperature shift on Cycle Day 14 (March 23).

This chart does not show a clear temperature shift. Her temperature spiked on Cycle Day 18 (March 16), but because it went back down the next day, it was not a true temperature shift.

This chart does not show a clear temperature shift. Her temperature spiked on Cycle Day 18 (March 16), but because it went back down the next day, it was not a true temperature shift.