Leveraging local real temperature data to accurately manage frost impact

Access to highly localised climate monitoring data is transforming how almond producers understand and manage the impact of severe weather events, particularly frost.

Data collected from individual weather stations on FrostBoss Frost Fans is providing unprecedented insights into frosts, enabling producers to assess the magnitude of frost occurrences and their effects on specific sections of an orchard.

Critically, this localised data identifies which orchard areas were protected during frost events and which were exposed, along with the duration of exposure. Producer scan use the information to adapt management strategies for affected areas, predict crop quality and refine yield forecasts.

The challenge of spring frosts

Spring frosts are particularly damaging for almond crops, freezing blossoms and young leaves, and destroying developing nutlets.

Such frosts are caused by factors including hot and dry summers, low winter rainfall, cool nights and lack of wind, which, when combined, create conditions ripe for frost.

However, the unpredictable nature of frosts in terms of timing and location makes them particularly difficult to manage, and the lack of precise yield monitoring at the orchard level has historically made it difficult for producers to quantify the extent of frost impact once the event has occurred.

Insights from the 2024 Spring Frost

The Spring frosts of 2024 serve as a stark example. Severe frost conditions swept across southernAustralia from September 15-18, affecting major almond growing regions including the Riverland, Riverina and Sunraysia. Prolonged dry winter conditions, clear nights and minimal wind caused temperatures to plummet below 0°C, with some areas experiencing lows below -3°C.

These frosts have been linked to significant yield losses, with some regions recording reductions of 10-30 per cent compared to the previous year.

While frosts are clearly not the only cause of yield loss, a spring frost undeniably has a major impact with the destruction of blossoms, leaves and nutlets reducing productivity.

As always, there were winners and losers in the September frosts.

Live climate monitoring data from weather stations on FrostBoss Frost Fans has shown orchards with the fans either avoided frosts entirely, or minimised their intensity and duration.

This data provides pinpoint accuracy, identifying affected orchard areas down to 6-7-hectare segments.

Case Studies – Riverland orchard

Data from a Riverland orchard in SA illustrates the insights available from the September 2024 frost.

The orchard installed frost fans based on climate mapping, which identified the orchard’s high frost-risk zones. Each fan covers 6-7ha and monitors two temperatures: the canopy temperature and the tower temperature, about 15m above the ground.

When the temperature drops to 0.9C, the fans automatically activate, drawing the warmer air down from the inversion layer into the cooler are among the almond trees to prevent crop damage. Data from these fans was analysed at three levels:

• Individual fan level: Temperatures at canopy and tower levels for each fan
• Orchard level: Aggregated data from all fans on the orchard
• Regional level: Data combined from FrostBoss frost fans across the region

Key Findings

Temperature son the orchard with FrostBoss frost fans for September 15-18 were compared with ambient weather data collected from across the region (Figure 1) and showed the following results:

• Orchards without frost fans in the Riverland faced sub-zero temperatures for an average of 4.4 hours,     compared to 30 minutes for orchards with fans.
• In the Sunraysia region, orchards without fans endured 2.4 hours below 0°C, compared to 1.8 hours     for those with fans.
• In the Riverina, orchards without fans were exposed to nearly two hours below 0°C, while orchards     with fans were exposed for only 12 minutes on average.

When reviewed across August and September, the contrast is even clearer, with exposure to sub-zero temperatures being reduced by 97% in the Riverland, 60% in the Sunraysia and84% in the Riverina (Figure 3) for orchards with frost fans.  

A further study of the data from individual fans shows the impact of frost on individual sections of the orchard. Figure 3 below shows,“Fan x” at the Riverland orchard stabilised canopy temperatures at 0.9°C when activated during each period of frost conditions over September 15-18.

Expert insights

Dr. Stu Powell, a climate scientist and frost expert from FrostConsult, highlights the importance of this data.

“After a frost, producers can review fan data to pinpoint exactly which orchard sections were affected and which remain unaffected,” he said.  “This eliminates the guesswork of scouting up and down rows for damaged areas.”

The data from August September also shows frost fans were automatically activated for 32 days, compared to the official 19 days of below-0C conditions recorded by Bureau of Meteorology stations in the regions.

“This shows conditions in the orchards can be significantly colder than conditions around BoM weather stations,” Dr Powell said. “This is particularly important for future almond plantings, providing more accurate information around climate conditions and the issues producers may face.”

Dr. Powell says the value of the data will be further realised when yield monitoring technology matches the granularity of frost fan weather station data.

“Once we can monitor harvest and yield at this level, producers will have an incredibly powerful tool for managing production and predicting outcomes.

“These fans have become more than just tools for frost mitigation, they are essential assets in the modern almond orchard, providing precise data that empowers producers to protect their crops, optimise yields and plan with confidence for future seasons.”