Pinewood nematode (PWN) is one of the most threatening invasive pests in the pine forests of Europe, and it has recently spread to the Iberian Peninsula via import of timber and wooden packaging material from East Asia. A cellular automaton (CA) model was developed to simulate and compare the potential spread of PWN by transportation and its vectors, Monochamus beetles in the pine forests of Finland and Iberian Peninsula. The model assumes that all pines are equally sensitive to PWN. The CA is a spatio-temporal grid-based model, which can easily be applied on different geographical scales. The effects of climate warming and number of entries from ports on the spread of PWN were studied. A sensitivity analysis was conducted on the most uncertain model parameters. Twenty years after hypothetical entries, the predicted area of symptomatic PWN infection (pine wilt disease, PWD) was very low in Finland compared to Iberia. This was because of the low probability of warm July in Finland. The increase in the mean July temperature increased the area of PWD-infected pine forest relatively more in Finland than in Iberia. An increase in the number of entries also increased the area of PWD-infected pine forest relatively more in Finland than in Iberia. The probability of PWD infection was the highest in pine forests that were close to entry points and in areas with low elevation and high human population density.