We examined variations in dart-throwing performance during the daytime in 12 participants. Two distances from the dartboard were investigated - the normal distance (short throws) and another 50% further away than this (long throws). Intra-aural temperature and subjective fatigue were measured, and errors in performance were assessed as the radial distances of throws from the bulls-eye and the standard deviation of these distances. Long-distance throws improved significantly throughout the daytime and correlated positively with intra-aural temperature (r = -0.49, P = 0.002 and r = -0.49, P = 0.002 for errors and standard deviation of errors, respectively), but not with subjective fatigue (r = -0.10, P = 0.56 and r = -0.05, P = 0.74 for errors and standard deviation of errors, respectively). Short-distance throws were associated less with intra-aural temperature (r = -0.46, P = 0.005 and r = -0.17, P = 0.31 for errors and standard deviation of errors, respectively), and worsened with fatigue (r = +0.34, P = 0.040 for errors). Compared with the short-distance throws, the long-distance throws were performed significantly less well than could be accounted for by the increased distance (mean errors were increased 1.67 - 2.78 times and standard deviation of errors of errors 1.58 - 3.68 times), supporting the concept of a trade-off between force of contraction and accuracy of performance. Throwing darts can be used as a model for investigating factors that influence motor performance, and our results indicate that the effects of time of day upon performance depend upon the relative importance of force and accuracy.