Climate Variables

SILO climate data are available for the following primary and derived variables on a daily timestep over the period 1889–present.

Climate data Variable Primary or
Short name/code Name in
API requests
Rainfall (mm) Daily rainfall Primary daily_rain R
Monthly rainfall Primary monthly_rain
Temperature (℃) Maximum temperature Primary max_temp X
Minimum temperature Primary min_temp N
Vapour pressure (hPa) Vapour pressure Primary vp V
Vapour pressure deficit Derived vp_deficit D
Evaporation (mm) Class A pan evaporation Primary evap_pan E
Synthetic estimate1 Derived evap_syn S
Combination (synthetic estimate pre-1970, class A pan 1970 onwards) Derived evap_comb C
Morton's shallow lake evaporation Derived evap_morton_lake L
Solar radiation (MJ/m2) Solar exposure, consisting of both direct and diffuse components Derived radiation J
Relative humidity (%) Relative humidity at the time of maximum temperature Derived rh_tmax H
Relative humidity at the time of minimum temperature Derived rh_tmin G
Evapotranspiration (mm) FAO564 short crop Derived et_short_crop F
ASCE5 tall crop6 Derived et_tall_crop T
Morton's areal actual evapotranspiration Derived et_morton_actual A
Morton's point potential evapotranspiration Derived et_morton_potential P
Morton's wet-environment areal potential evapotranspiration over land Derived et_morton_wet W
Mean sea level pressure (hPa) Mean sea level pressure Derived mslp M

 Monthly rainfall has a monthly timestep.

In point datasets Class A pan evaporation data are shifted to the previous day (see the FAQ "Why are evaporation data shifted to the day before?").

 Metadata describing the primary variables and the procedures used to construct them are available in the Queensland Spatial Catalogue.

Variable information

 Solar radiation: total incoming downward shortwave radiation on a horizontal surface, derived from estimates of cloud oktas and sunshine duration3.

 Relative humidity: calculated using the vapour pressure measured at 9am, and the saturation vapour pressure computed using either the maximum or minimum temperature6.

  Evaporation and evapotranspiration: an overview of the variables provided by SILO is available here

 Publications referenced

  1. Rayner, D. (2005). Australian synthetic daily Class A pan evaporation. Technical Report December 2005, Queensland Department of Natural Resources and Mines, Indooroopilly, Qld., Australia, 40 pp.
  2. Morton, F. I. (1983). Operational estimates of areal evapotranspiration and their significance to the science and practice of hydrology, Journal of Hydrology, Volume 66, 1-76.
  3. Zajaczkowski, J., Wong, K., & Carter, J. (2013). Improved historical solar radiation gridded data for Australia, Environmental Modelling & Software, Volume 49, 64–77. DOI: 10.1016/j.envsoft.2013.06.013.
  4. Food and Agriculture Organization of the United Nations, Irrigation and drainage paper 56: Crop evapotranspiration - Guidelines for computing crop water requirements, 1998.
  5. ASCE’s Standardized Reference Evapotranspiration Equation, proceedings of the National Irrigation Symposium, Phoenix, Arizona, 2000.
  6. For further details refer to Jeffrey, S.J., Carter, J.O., Moodie, K.B. and Beswick, A.R. (2001). Using spatial interpolation to construct a comprehensive archive of Australian climate data, Environmental Modelling and Software, Volume 16/4, 309-330. DOI: 10.1016/S1364-8152(01)00008-1.

For a full list of publications relevant to SILO data, please see the Publications and references page.

Last updated: 7 July 2021