The paper explores temporal changes within an intonational phrase in Russian. The main question we aim to answer is whether we can speak about temporal “declination” in a similar way we speak about melodic declination. In order to answer this question, we analysed stressed vowel duration in intonational phrases (IPs) of different types using a speech corpus. We have found that (1) most intonational phrases in Russian do not have temporal “declination” or “inclination” in the pre-nuclear part: the tempo is relatively stable until the nucleus, where a noticeable lengthening is observed; (2) the rarely occurring temporal “declination” or “inclination” in certain types of IPs can be considered a specific speaker’s trait; (3) the amount of lengthening on the last stressed vowel within the IP may play a role in distinguishing final and non-final IPs, rising vs. falling nuclei, but this is also speaker-specific.