Guidelines for Celsius Temperatures
Thermometers
Digital Thermometer
A basal thermometer with two decimals is needed. An ordinary fever thermometer with only one decimal is not adequate.
For example, 36.5 is not enough. It should be able to detect 36.55.
Glass Thermometer
Either fever or basal is fine, if you can read when the liquid lands in between lines.
For example, if it falls between 36.5 and 36.6, it’s charted as 36.55.
Examples of Rounding Up or Down When Using a Celsius Digital Thermometer
| Temp Taken | Temp Rounded |
| 36.60 36.59 36.58 |
36.60 |
| 36.57 36.56 36.55 36.54 36.53 |
36.55 |
| 36.52 36.51 36.50 |
36.50 |
How to Draw the Coverline
Look for the first temperature that is at least 0.1°C (two spaces) above the last 6 lower temps.
Draw the coverline 0.05°C above the highest of the last 6 low temps.
Thermal Shift Rule for Various Patterns
| Page in U.S. Book | Thermal Shift Types | When You Are Safe | |
Standard |
174 | The first time a temperature is at least 0.1°C above the highest of the last 6 lows and is sustained for at least 3 days. | If the 3rd high temp is |
Weak or |
435 438 |
When the 3rd temp doesn't reach 0.15°C above the coverline. | If the 4th high temp is anywhere above the coverline. |
| Slow-Rise | 436 | When temps rise only 0.05°C at a time, the coverline is drawn through the first temp that rises 0.05°C above the highest of the last 6 temps. | If the 3rd high temp above the coverline is at least 0.15°C above. |
| Fallback | 439 | When the 2nd or 3rd temp falls back on or below the coverline, the temp count is restarted. | If 3rd temp of the new count is at least 0.15°C above the coverline. |
Thermal Shift Rule for Various Patterns
(If viewing this on your phone, swipe right to left to review whole table)
| Page in U.S. Book | Thermal Shift Types | When You Are Safe | |
Standard |
174 | The first time a temperature is at least 0.1°C above the highest of the last 6 lows and is sustained for at least 3 days. | If the 3rd high temp is |
Weak or |
435 438 |
When the 3rd temp doesn't reach 0.15°C above the coverline. | If the 4th high temp is anywhere above the coverline. |
| Slow-Rise | 436 | When temps rise only 0.05°C at a time, the coverline is drawn through the first temp that rises 0.05°C above the highest of the last 6 temps. | If the 3rd high temp above the coverline is at least 0.15°C above. |
| Fallback | 439 | When the 2nd or 3rd temp falls back on or below the coverline, the temp count is restarted. | If 3rd temp of the new count is at least 0.15°C above the coverline. |
If the 3rd temp of the Slow-Rise or Fallback doesn’t meet the 0.15°C criteria, you should wait for an additional, 4th temp anywhere above the coverline. The Slow-Rise and Fallback should not be combined unless you have an extremely obvious Peak Day and your Cervix can corroborate your fertility status, as well.
ALWAYS wait until both the Thermal Shift and Peak Day Rules are met before considering yourself safe.
Standard Shift
Weak Stairstep Shift
Slow Rise Shift
Fall Back Shift
