Does your temperature rise before your period?
Yes. After ovulation, progesterone raises your resting body temperature by about 0.3 to 0.5°C (0.5 to 1°F), and it stays higher through the luteal phase. In the day or two before your period, as progesterone falls, your temperature usually drops back down. If it stays high for 18 days or more after ovulation, pregnancy is possible.
How temperature moves through your cycle
Your basal body temperature (BBT) is your temperature at complete rest, usually measured first thing in the morning before you get up. It follows a two-step pattern in an ovulatory cycle:
| Cycle stage | What temperature usually does |
|---|---|
| Period and follicular phase | Lower baseline |
| Ovulation | Sometimes a tiny dip, then a rise within a day or two |
| Luteal phase | Stays about 0.3 to 0.5°C (0.5 to 1°F) higher |
| 1 to 2 days before your period | Often drops as progesterone falls |
| Early pregnancy | Stays high instead of dropping |
The rise happens because progesterone acts on the part of the brain that sets body temperature. The temperature shift confirms ovulation after it has happened, so it can't predict ovulation in the current cycle, but it can show your pattern over time. More in what basal body temperature is.
Why you might feel hot before your period
That higher luteal temperature is small, but some people notice it as feeling warmer, sweating more at night, or sleeping less well. Warmer nights in the second half of the cycle are one reason sleep can get lighter before a period. Hot flashes before a period are also common in perimenopause, when estrogen swings more widely. See feeling hot before your period and hot flashes before period.
What your temperature can and can't tell you
- It can show that you probably ovulated, and roughly when, once the rise has held for about 3 days.
- It can help you see how long your luteal phase is.
- It can hint at pregnancy if it stays high for 18 days or more after ovulation. A test confirms it.
- It can't predict ovulation ahead of time in the current cycle.
- It can't be read reliably after poor sleep, alcohol, illness or a late night, which all nudge it.
Wearables like Apple Watch measure skin temperature overnight rather than oral BBT. The pattern is similar, but the numbers aren't the same, and Apple describes its ovulation estimates as retrospective. Use either as a guide, not a guarantee.
Temperature and mood before your period
The same days your temperature is high are the days progesterone is high, and then falling. For many people that's when PMS shows up: tiredness, irritability, tears, cravings. Seeing your temperature drop can be a quiet signal that your period, and often some relief from PMS, is close.
See a doctor if you have a real fever (38°C / 100.4°F or higher), night sweats that soak your sheets, or hot flashes that disrupt your sleep or life. These aren't explained by normal cycle changes.
Frequently asked questions
Does your temperature drop right before your period?
Often, yes. It usually falls in the day or two before bleeding as progesterone drops, though some people see it fall on day 1.
What temperature means I'm pregnant?
There's no single number. A temperature that stays above your usual luteal level for 18 days or more after ovulation suggests pregnancy, and a test can confirm it.
Is a high temperature before my period a fever?
No. The luteal rise is less than 0.5°C. A reading of 38°C (100.4°F) or more is a fever and has another cause.
Can I use temperature to avoid pregnancy?
Temperature alone isn't reliable for that, because it only confirms ovulation afterwards. Lulu is not contraception: talk to a clinician about methods that suit you.
Sources
- Cleveland Clinic: Basal Body Temperature
- ACOG: Fertility Awareness-Based Methods of Family Planning
- Su HW et al. Detection of ovulation, a review of currently available methods. Bioeng Transl Med (2017)
- Baker FC, Lee KA. Menstrual Cycle Effects on Sleep. Sleep Med Clin (2018)
This page is for information only and isn’t medical advice. If something worries you, please talk to a doctor.
Keep reading
What is basal body temperature, and what can it tell you?Basal body temperature is your resting temperature on waking. It rises slightly after ovulation. How to measure it, read a BBT chart, and its limits.How does Apple Watch wrist temperature work for cycles?Apple Watch wrist temperature tracks nightly changes from your baseline. How it relates to your cycle, how to read the chart, and what affects it.
Why do I feel hot before my period?Feeling hot before your period is common. Progesterone raises body temperature after ovulation, and falling estrogen can bring night sweats. What helps.
Luteal phase: why feelings get louderWhat the luteal phase is, how long it lasts, why progesterone rises and falls, and the common symptoms: PMS, cravings, low energy and mood changes.
Luteal phase calculator: how long is my luteal phase?Free luteal phase calculator: enter your ovulation day and next period to see your luteal phase length and whether it sits in the typical 11 to 17 day range.