When learning from text, it is important that learners not only comprehend the information but also accurately monitor and judge their comprehension, known as metacomprehension accuracy. We investigated the extent to which the achievement emotions high school students (N = 358) experienced during reading influenced their text comprehension, metacomprehension judgments, and metacomprehension accuracy. The results of our correlational analyses indicated that more negative emotions (i.e., anger, hopelessness, and negative emotions overall) were related to poorer text comprehension (small to small-to-medium correlations). Moreover, the students generally used their emotions as cues for making predictions and postdictions about their comprehension (small to medium-to-large correlations). However, concerning prediction accuracy, more positive emotions (i.e., enjoyment, hope, pride, and positive emotions overall) were associated with greater overconfidence and more negative emotions (i.e., anxiety, shame, and hopelessness) with greater underconfidence (small to small-to-medium correlations). Concerning postdiction accuracy, more positive emotions (i.e., enjoyment, hope, pride, and positive emotions overall) were associated with less underconfidence and more negative emotions (i.e., anxiety and shame) with greater underconfidence (small correlations). The results of our cluster and variance analyses largely converged with the correlational results. Consequently, achievement emotions do not necessarily represent valid cues for judging comprehension and can lead to inaccurate metacomprehension, hindering effective self-regulated learning from texts.