Abstract Data on predicted average and maximum air- borne pollen concentrations and the dates on which these maximum values are expected are of undoubted value to allergists and allergy sufferers, as well as to agronomists. This paper reports on the development of predictive models for calculating total annual pollen output, on the basis of pollen and weather data compiled over the last 19 years (1982–2000) for Córdoba (Spain). Models were tested in order to predict the 2000 pollen season; in addi- tion, and in view of the heavy rainfall recorded in spring 2000, the 1982–1998 data set was used to test the model for 1999. The results of the multiple regression analysis show that the variables exerting the greatest influence on the pollen index were rainfall in March and temperatures over the months prior to the flowering period. For pre- diction of maximum values and dates on which these values might be expected, the start of the pollen season was used as an additional independent variable. Temper- ature proved the best variable for this prediction. Results improved when the 5-day moving average was taken into account. Testing of the predictive model for 1999 and 2000 yielded fairly similar results. In both cases, the dif- ference between expected and observed pollen data was no greater than 10%. However, significant differences were recorded between forecast and expected maximum and minimum values, owing to the influence of rainfall during the flowering period. Keywords Aerobiology · Forecasting · Olea europaea · Pollen Index · Pollen Production Introduction The olive tree Olea europaea L. is one of the most char- acteristic features of Mediterranean flora. Olives and olive oil are among the oldest and most important products in this part of the world. The region of Anda- lusia has by far the largest area of olive plantations, amounting to 1,192,107 ha in 1999 with more than 154×10 6 trees. It therefore accounts for 80% of the Span- ish total, the province of Córdoba ranking second to Jaén in terms of output, with 277.237 ha in 1999. From the to- tal of 3,481,558 Tonnes were picked in Córdoba (Anda- lusia Statistical Yearbook, Anuario Estadístico de Anda- lucía 1999). Studies of the O. europaea pollen season are important for two major reasons. First, because of the surface area it occupies in Andalusia, the olive crop is among the most significant local causes of allergy; this tree produces al- lergenic pollen grains both in Mediterranean and general climates (D’Amato and Liccardi 1994) and in the city of Córdoba in particular (Domínguez-Vilches et al. 1993), where pollen even 70 km away is detectable (Fornaciari et al. 2000). Florido et al. (1999) reported that more than 400 g/m 3 is enough to provoke symptoms in patients clinically sensitive to olive pollen in the south of Spain. Second, atmospheric pollen can be used as a bioindicator of fruit production, which is then applicable in agronom- ic studies (González-Minero et al. 1998). For this reason, several papers have focused on the aerobiology of olive trees in Spain (Candau et al. 1981; Domínguez et al. 1993; Díaz de la Guardia et al. 1993; Recio et al. 1996; González-Minero and Candau, 1997; Gutierrez Bustillo and Sáenz-Laín, 2000; Ruiz et al. 1998). Some authors have attempted to define the pollen sea- son of the olive, while others have studied the start of the pollen season using meteorological data from the pre- flowering period. It is generally agreed that temperature is one of the main parameters affecting onset (Alba and Díaz de la Guardia, 1998; Frenguelli et al. 1989; Fornaciari et al. 1998; González-Minero and Candau Fernández-Mensaque, 1996; Galán et al. 2001). Howev- Dr. C. Galán ( ✉ ) · Dr. P. Cariñanos · Bc.Sc. H. García-Mozo Dr. P. Alcázar · Dr. E. Domínguez-Vilches Department of Botany, Colonia San José, casa 4, Campus Universitario de Rabanales, University of Cordoba, Ctra. Madrid, Km. 396, 14071 Córdoba, Spain e-mail: bv1gasoc@uco.es Tel.: +34-957-218719, Fax: +34 957 218598 Int J Biometeorol (2001) 45:59–63 © ISB 2001 ORIGINAL ARTICLE Carmen Galán · Paloma Cariñanos Herminia García-Mozo · Purificación Alcázar Eugenio Domínguez-Vilches Model for forecasting Olea europaea L. airborne pollen in South-West Andalusia, Spain Received: 25 October 2000 / Revised: 26 February 2001 / Accepted: 28 February 2001