Bureau of Meteorology


The BOM Blog gives you the background and insider info on weather, climate, oceans, water and space weather—as well as the latest on the work of the Bureau.


Our blog platform no longer supports comments.

You can contact us at bomblog@bom.gov.au.

Copyright | Disclaimer | Privacy


Contact our social media team at socialmedia@bom.gov.au

A week of rain: Detailed rainfall information to land on all précis forecasts

A week of rain: Detailed rainfall information to land on all précis forecasts

In the latest expansion of our popular précis service, we are adding detailed rainfall data to all 679 city and town forecasts.

The précis forecasts that many Australians rely on for their first glance at the weather each morning are about to get a well-earned facelift, bringing a new level of rainfall detail to help people plan their day—and check out the week ahead.

All 679 city and town locations that receive a précis forecast will now receive a ‘metropolitan-style’ weather summary, with a handy graphic of the ‘chance of any rain’ and ‘possible rainfall’ amounts for each of the next seven days.

Alongside these at-a-glance graphics, the précis text summaries will continue to give you the detail of the times of day when rain is most likely to fall in your location.

Tracking the rain

Up to now, most towns have had little rainfall information on our précis service, which is widely used by TV and radio weather summaries and appears on the weather pages of many popular newspapers. Where rainfall figures were provided, they were usually only for the current day.

Example of rainfall information in forecasts

Figure 1 Example of the rainfall information to be presented in forecasts.

In the new format, all urban locations will now feature the ‘chance of any rain’ and ‘possible rainfall' amounts as illustrated in the image above.

Figure 2 Example of the previous Précis Forecast

The new look précis

The new look précis forecast (example below) will include rainfall information for tomorrow and the week ahead in all city and town locations.

The forecast for the current day will be slightly different to the other days of the week, as it will give a ‘chance of any rain for the rest of the day’ and only include ‘possible rainfall' amounts at some locations.

The ‘chance of any rain’ provides a value that refers to the likelihood of receiving more than the minimum measurable amount of rainfall (0.2 mm) over the 24 hours of that day. The higher the percentage, the greater the chance of needing your brolly!

The ‘possible rainfall’ amount provides a range between two values—the first representing a 50 per cent chance of receiving at least that amount, and the second representing a 25 per cent chance of receiving at least that amount. So for a forecast of '2 to 5 mm', the location would have a 50 per cent chance of getting 2 mm or more, and a 25 per cent chance of getting 5 mm or more.

The range works as follows:

  • When the daily chance of rain is less than 50 per cent, the range will start at 0 mm.
  • When the daily chance of rain is more than 50 per cent, then the lower range value will be non-zero.
  • When the daily chance of rain is less than 25 per cent, no rainfall range will be shown.

Figure 3 Example of the New Look Précis Forecast

Comment. Tell us what you think of this article.

Share. Tell others.