Wow -- St. Thomas had quite the mind! An excerpt from the Summa:


    In the second place, acts of the free-will, which is the faculty of will and reason, escape the causality of heavenly bodies. For the intellect or reason is not a body, nor the act of a bodily organ, and consequently neither is the will, since it is in the reason, as the Philosopher shows (De Anima iii, 4,9). Now no body can make an impression on an incorporeal body. Wherefore it is impossible for heavenly bodies to make a direct impression on the intellect and will: for this would be to deny the difference between intellect and sense, with which position Aristotle reproaches (De Anima iii, 3) those who held that "such is the will of man, as is the day which the father of men and of gods," i.e. the sun or the heavens, "brings on" [Odyssey xviii, 135].

    Hence the heavenly bodies cannot be the direct cause of the free-will's operations. Nevertheless they can be a dispositive cause of an inclination to those operations, in so far as they make an impression on the human body, and consequently on the sensitive powers which are acts of bodily organs having an inclination for human acts. Since, however, the sensitive powers obey reason, as the Philosopher shows (De Anima iii, 11; Ethic. i, 13), this does not impose any necessity on the free-will, and man is able, by his reason, to act counter to the inclination of the heavenly bodies.

There are COUNTLESS things that can (and often do) affect our physical and emotional natures and can put our spiritual natures to the test:  everything from allergies, to pesticides, illnesses of all kinds and simply the onset of illness, lack of nutrients, lack of sleep, lack of exercise (can actually affect your hormones, for example), stress, you name it.

It's still very relevant and very important to mention here that any time someone tries to predict the future (I'm not talking like speculation, i.e., in politics, financial investments, etc.), but in the sense of a non-science, like astrology, it is a mortal sin against the 1st Commandment.  The reason being is because it is trying to know something that only God can know.  Also, evil spirits can (and often do) oppress those who even tinker with such things as astrology, talking to the dead, psychics, etc.  I realize that most of us know this already, but I just wanted to sound off on it again for those who might be confused.