Abstract Part 3 of this study presents details of an investigation into the fluctuating pressures and loads induced on smooth, cantilevered circular cylinders immersed in a low-turbulence, uniform flow. Experiments were carried out in a wind tunnel at a Reynolds number of 4·4 × 104 for aspect ratios in the range 4 to 25. R.m.s. pressures on the surface of the cylinder and r.m.s. lift and drag were measured, and the frequency content of the fluctuation was analysed. The results are consistent with the mean loading pattern presented in Part 1, particularly with regard to the existence of a significant aspect ratio of 13, and complete the data set for aspect ratios in the range 4 to 30.