Audax rides take place in a range of weather conditions, and conditions can change over the course of a long ride.
Monitor the weather forecasts leading up to a ride, taking note of temperature maximums and minimums, winds, rain, etc.
Websites such as 
BOM and 
Windy are very useful.
There are also apps that marry weather forecasts with GPS data to predict conditions around your route, such as Epic Weather Ride App which is linked to RideWithGPS.
Tailor your clothing and sustenance choices to the conditions and, as always, err on the side of carrying more rather than less (see Clothing and Ride Safety/Sustenance).
Reference: Audax Australia Safety Rules
There are considerations for Audax rides when extreme weather conditions exist, including hot and cold weather, rain and flooding, wind, storms, or near bushfires.
All club members are urged to consider that extreme conditions have the potential to put the health and lives of both riders and ride support crews at risk. As well as considering the specific points below, the key is to know your own limits, to recognise your responsibility for your own safety, and to apply caution together with commonsense in these conditions.
Strenuous exercise in hot weather increases the risk of heat illness, which can lead to more serious and potentially life-threatening conditions.
Audax does not allow unsupported rides to proceed when the forecast maximum temperature is above 36oC and has special conditions for supported rides of 200km or more in such temperatures (see Audax Australia Safety Rules).
As a rider, you should consider whether you are sufficiently fit and healthy before commencing a ride on a hot day. Pace yourself during the ride and take on plenty of fluids, and of course stop to recuperate or withdraw from a ride before you find yourself in trouble (see Ride Safety/Sustenance for more info).
While Australia generally does not experience the extreme cold of places such as Canada and northern Europe, the mercury can hover below or around zero oC for many hours on some rides in winter, particularly in inland parts of the southern states, and in alpine areas. (Be aware that temperatures can plummet and the weather deteriorates quickly in alpine areas). The cold can be exacerbated if accompanied by mist, sleet or rain.
If you may be riding in these conditions, as well as appropriate clothing, many experienced Randonneurs carry a space blanket in case of emergency.
Riding through areas of heightened fire danger poses obvious health and safety risks. Audax rides are not conducted through areas declared to have an ‘Extreme’ or ‘Catastrophic/Code Red’ fire danger rating, and may also be cancelled, postponed or re-rerouted on days when the fire danger is rated ‘Severe’ (see Audax Australia Safety Rules).
If you are on a ride during the fire season it is advisable to monitor fire conditions using relevant websites or apps (see below) and to apply appropriate caution if a fire is burning in proximity to the route. Also, be aware of the risk that you will encounter smoke on such rides (see Air quality below).
Useful websites for monitoring bushfire activity include:
NSW and ACT
Victoria
Queensland
South Australia
Western Australia
Tasmania
Northern Territory
Most of these sites also have apps that provide current information on the location and status of fires that can be downloaded to your phone.
Other than wearing appropriate attire and taking due care on the road, riding in the rain or on windy days requires no special caution. However, if you are riding into or become caught in a hailstorm or a thunderstorm with lightning strikes nearby, or with severe wind gusts that might blow you off or across the road, you should of course seek shelter until the activity passes.
Although rare, it is possible to encounter smog, smoke or raised dust on Audax rides. These may cause irritation of the eyes and, when inhaled, trigger respiratory conditions such as asthma, coughing or inflammation of the lungs and airway. Continued exposure can have other adverse health effects, and smoke and raised dust can also affect visibility on the road. Air quality can be one factor Audax takes into account when deciding whether to run rides.
‘Air Quality Indexes’ are used to provide advice on air quality and associated health risks.