IFD General Data Info
The whole of Australia is covered by the BoM IFD dataset that was last updated in 2016 and is based on rainfall data up to 2012.
Since the Bureau of Meteorology (BoM) published Australia wide IFD's in 2016 there has been updated IFD's for specific locations in Australia. IFD updates in the Illawarra and Coffs Harbour regions of NSW was driven by the very localised orographic enhancement not being captured by BoM IFD. In both locations the update was a result of a large number of non BoM rainfall gauges showing very different results to the BoM IFD.
In 2020 a new IFD dataset was produced for Brisbane, Ipswich, Lockyer and Moreton Bay Councils (LIMB IFD). This IFD update was a result of concerns about the BoM IFD not capturing some of the spatial variability observed within the network of gauges, and the large number of extreme rainfalls recorded in the previous decade.
A similar IFD update was carried out in the Gold Coast region though this data has not been published. In 2025 QRA commissioned a IFD update for the coastal catchments from the NSW border to Bundaberg.
In 2024 the new climate change considerations chapter of ARR outlined how frequency based estimates could be adjusted for climate change using the midpoint of the underlying data. This allowed these data sets to be adjusted to a common historical (1960-1990) baseline and scaled to future climate conditions. For some datasets the midpoint was slightly later than 1990, but given the uplift was very small, the historical baseline was used. This is shown in Table 1 below. For consistency, the ARR datahub produces 2030 IFD's by default to represent the current climate.
| Source | Nominal Midpoint |
|---|---|
| BoM | 1961 - 1990 |
| Illawarra | Sub-Daily: 2002, Daily: 1961-1990 |
| Coffs Harbour | Sub-Daily: 2002, Daily: 1961-1990 |
| LIMB | Sub-Daily: 2002, Daily: 1961-1990 |
| QRA | 2010 |
Recommended IFDs
Regions and LGAs that have opted to have a recommended IFD are included in the table below.
For regions not listed, the default BoM IFD is recommended.
| Region | Recommended IFD* |
|---|---|
| Bundaberg | QRA SEQ 2025 IFD*^ |
| North Burnett | QRA SEQ 2025 IFD*^ |
| Fraser Coast | QRA SEQ 2025 IFD*^ |
| South Burnett | QRA SEQ 2025 IFD*^ |
| Cherbourg | QRA SEQ 2025 IFD*^ |
| Gympie | QRA SEQ 2025 IFD*^ |
| Noosa | QRA SEQ 2025 IFD*^ |
| Sunshine Coast | QRA SEQ 2025 IFD* |
| Somerset | QRA SEQ 2025 IFD*^ |
| Scenic Rim | QRA SEQ 2025 IFD* |
| Toowoomba | QRA SEQ 2025 IFD*^ |
| Lockyer Valley | Envelope(LIMB 2020 IFD, QRA SEQ 2025 IFD)* |
| Ipswich | Envelope(BoMIFD, LIMB 2020 IFD)* |
| Moreton Bay | LIMB 2020 IFD* |
| Brisbane | Envelope(LIMB 2020 IFD, QRA SEQ 2025 IFD)* |
| Gold Coast | QRA SEQ 2025 IFD*^ |
| City of Wollongong LGA | Illawarra IFD* |
| City of Coffs Harbour LGA | Coffs Harbour IFD* |
*Current recommended IFDs are draft and may not represent the regions' final recommendation.
^No decision has been made, defaulting to the QRA SEQ 2025 IFD.