The basal body temperature (BBT) varies from person to person and also depends on where you measure it. You can measure your basal body temperature orally, vaginally, or rectally.
Measurement of the temperature vaginally or rectally provides higher temperatures than measuring orally. It is important that you always measure in the same way and the same place.
If you would like to change your way of measuring, you should always do so at the start of a new cycle. It can then take around 1-3 cycles for the algorithm to adjust to your new way of measuring, and during this time you can expect to be given a bit more red days (for NC° Birth Control) or brown days (for NC° Plan Pregnancy).
Note: If you are struggling with your measuring routine, know that you now have the option to use Natural Cycles with an Oura Ring. When wearing an Oura Ring, your temperature trends get measured overnight while you sleep. This means that you no longer need to measure with your oral thermometer as soon as you wake up! Learn more here.