In the current paper, the effect of curling and warping, caused by environmental ambient conditions, on the initial smoothness of concrete pavements is discussed. Surface profile measurements were made during the hours of the early morning and late afternoon on an instrumented jointed plain concrete pavement (JPCP) on highway US-30 near Marshalltown, Iowa during the first seven days after construction in summer 2005. Variations in temperature and moisture during this critical period were monitored using the temperature and relative humidity sensors installed within the test sections at the time of construction. Based on the measured surface profile data, it was observed that the initial pavement smoothness, in terms of international roughness index (IRI) and the ride number (RN), was not significantly influenced by the early-age curling and warping behaviour of the JPCP. Using finite-element modelling (FEM), sensitivity studies were conducted to investigate the influence of slab curvature on initial pavement smoothness for a range of equivalent temperature differences between the top and bottom of the slab. The results indicated that the initial JPCP smoothness is sensitive to changes in slab curvature resulting from environmental ambient conditions only at higher magnitudes. Although the FEM-based IRI predictions were higher than the surface profile-based IRI values, the differences were not significant.