International Journal of Biometeorology

, Volume 58, Issue 5, pp 669–678 | Cite as

Weather factors in the short-term forecasting of daily ambulance calls

  • Ho-Ting Wong
  • Poh-Chin LaiEmail author
Original Paper


The daily ambulance demand for Hong Kong is rising, and it has been shown that weather factors (temperature and humidity) play a role in the demand for ambulance services. This study aimed at developing short-term forecasting models of daily ambulance calls using the 7-day weather forecast data as predictors. We employed the autoregressive integrated moving average (ARIMA) method to analyze over 1.3 million cases of emergency attendance in May 2006 through April 2009 and the 7-day weather forecast data for the same period. Our results showed that the ARIMA model could offer reasonably accurate forecasts of daily ambulance calls at 1–7 days ahead of time and with improved accuracy by including weather factors. Specifically, the inclusion of average temperature alone in our ARIMA model improved the predictability of the 1-day forecast when compared to that of a simple ARIMA model (8.8 % decrease in the root mean square error, RMSE = 53 vs 58). The improvement in the 7-day forecast with average temperature as a predictor was more pronounced, with a 10 % drop in prediction error (RMSE = 62 vs 69). These findings suggested that weather forecast data can improve the 1- to 7-day forecasts of daily ambulance demand. As weather forecast data are readily accessible from Hong Kong Observatory’s official website, there is virtually no cost to including them in the ARIMA models, which yield better prediction for forward planning and deployment of ambulance manpower.


Emergency ambulance service Time series analysis Autoregressive integrated moving average model Weather 



The research is supported in part by (1) Hui-Oi-Chow Trust Fund, the University of Hong Kong, and (2) General Research Fund, Research Grants Council of Hong Kong. We are grateful to the following government departments of the Hong Kong Special Administrative Region for data access: Hong Kong Observatory and Hospital Authority.

Competing interest

None to declare.

Ethical considerations

Ethical approvals have been obtained from the University of Hong Kong Human Research Ethics Committee for Non-Clinical Faculties.


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Copyright information

© ISB 2013

Authors and Affiliations

  1. 1.Department of GeographyThe University of Hong KongHong KongPeople’s Republic of China
  2. 2.School of Medicine and Health ManagementTongji Medical College of Huazhong University of Science and TechnologyWuhanPeople’s Republic of China

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