Some women find that they can pinpoint their time of ovulation more easily if they keep track of their temperature, which rises close to the time of ovulation. To do this, you take your temperature (orally) each morning before you get out of bed. It typically reaches its lowest point right before your pituitary gland releases luteinizing hormone (LH), which triggers ovulation. (Two days after the so-called LH surge, your temperature rises significantly — about a half to one degree above baseline — and stays elevated until you get your period. If you get pregnant, it remains high.) You may want to invest in a special "basal body temperature" thermometer (sold in most drug stores) because it has larger gradations and is easier to read.
Remember that a rise in your basal body temperature indicates that ovulation has already occurred. It doesn't predict when you will ovulate, but it does confirm that you're ovulating, and gives you a rough idea when ovulation occurs in your cycle.
Reading the signals can sometimes be hard because not all women follow the same pattern. Some never see a distinct drop in temperature, and some never see a clear rise.
Another way to monitor the LH surge is to use a home ovulation predictor kit, which tests the amount of LH in urine. As opposed to basal body temperatures mentioned previously, the LH surge is useful in predicting when ovulation will occur during any given cycle. A positive test for any cycle tells you that you're ovulating and when. In general, these kits are very accurate and effective. The main drawback is the expense. At $20 to $30 per kit, they're more expensive than taking your temperature.
A new way of checking for ovulation is now available, which involves testing saliva instead of urine. The increased estrogen levels that occur around the time of ovulation cause the saliva to form a crystallized pattern upon drying. Both the urine tests and saliva tests are equally accurate at predicting ovulation. The saliva kit is a little pricier at $60, but you can use it for up to one year.