Numerical models of the marine wind field and wave generation offer a techn
ique for estimating the severity of extreme wave events. Measured and model
led waves in the Canterbury Eight, New Zealand, were used to examine the hy
pothesis that extreme conditions can be more confidently estimated by model
ling the wave climate over a decade than by analysing shorter measured reco
rds. The meteorological conditions causing high waves in the Canterbury Eig
ht were examined by inspecting wind measurements at Christchurch Airport an
d wave buoy measurements made in 1983-85 near the Rakaia River mouth. Altho
ugh the arrival of high waves was sometimes associated with wind changes at
the airport, peak wave heights generally occurred at least several hours a
fter such wind changes and were associated with south-westerly or southerly
winds in the Bight and a depression south-east of the South Island. Wave c
onditions at the buoy site for 1980-89 were modelled using marine winds obt
ained from a global circulation model, running a wave generation model for
the seas around New Zealand, and then applying a refraction model. The deca
de modelled included two El Nino events and one La Nina event, and the ocea
n wind climate should therefore have been reasonably representative of the
long-term range of conditions. The model results were verified against the
buoy measurements. Estimates of extreme wave heights were then made from 10
years of modelled record and also the measured buoy record. Application of
the Gumbel distribution to the monthly maxima gave a significant wave heig
ht of 9.5 m for the wave event with an annual exceedance probability of 1 i
n 50. Model predictions indicate that the most severe waves arrive in the B
ight from due south. Estimates of extremes from the measurements and model
hindcast were close, indicating that the hindcast represents a population o
f events similar to those measured.