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Leap Year’s Weather History: Jumping to 2024’s Crop Impact

Scott Patterson • February 28th, 2024.

2024 Storm Tracks North America

Some folklore says bad weather is worse in leap years. While extreme weather has occurred in previous leap years, there is no scientific connection between the two. Even so, let’s explore the bad weather from previous leap years and jump ahead to what might occur over the rest of 2024.

Leap Years and Bad Weather Since 2004

Overview of 2024

El Niño will end between June and August, with La Niña returning sometime toward the end of the year. The effects of El Niño may linger well beyond its official end. With La Niña trying to start up, there could definitely be some chaotic weather worldwide as 2024 closes out.

Regions to Monitor

Canadian Prairies to the Iowa Corn Belt

Drier than normal conditions in 2023 and lower than normal snowpack over the 2023-2024 winter season will lead to, at a minimum, short-term drought concerns for wheat, corn, and barley. March, April, and May can see periods of heavier rainfall, but there is high uncertainty that will occur this year because El Niño will still be in control through at least June and favors a warmer, drier pattern. If the spring continues to be dry, then concern will increase that the summer will be drier than normal as well, which has a negative impact on fall harvests.

Drought Risk Areas - Wildfires, Barley, Wheat and Corn in North America

Fig 1. The agricultural regions where Barley, Wheat and Corn are grown in Canada
and the US. Wheat is also grown in Kansas. Wildfires are a concern again in 2024
in northern BC, Alberta and near Yellowknife. Because of the jet stream, the
smoke could head towards the Northeast US, similar to 2023. 

While drought doesn’t necessarily mean warmer temperatures, drier soil is susceptible to warmer than normal temperatures, which could further affect crops through heat stress.

On a side note, the area of northern BC, northern Alberta, and southern Northwest Territories is currently in a severe to extreme drought. This is the same area that saw massive wildfires in 2023, which led to extensive smoke across Canada and the United States and will be a concern again in 2024.

2024 Storm Tracks North America

Fig 2. El Niño in the spring/summer leads to a northern jet stream that dives into the US from
western Canada, taking all the moisture into eastern Canada/US. A second possible
storm track is the northern jet stream diving south, but further west into the southwest US,
still leading to a dry north-central US and central Canada. The southern jet stream,
which has the moisture, stays south leading to more rain and clouds through
southern California, southern Texas, and along the east coast of the US.

Equatorial Impacts to South America, Africa, India, Southeast Asia

Many crops like soybeans, sorghum, corn, coffee, and chocolate were affected by shifting rainfall patterns in 2023. 2024 looks to be more of the same through the middle of the year before El Niño finally ends. As the year unfolds, the main risk is that the El Niño will once again influence the growing season by throwing off the timing of the wet season. Again, intermittent periods of heavy rainfall and flooding, mixed with long stretches of heat stress and dry conditions will make conditions difficult for crops. These types of chaotic, back and forth type weather patterns will encourage lower yields at harvest, as crops are unable to rebound during favorable weather. India will continue to see a risk of a drier, slower than normal monsoon. Unlike last year, India will not be affected by a positive IOD phase, which was likely a big contributor to the crazy rainfall differences from one province to another, in 2023.

Chaotic Precipitation Patterns - South America, India, Africa, Asia

Fig 3. Shifting rainfall patterns will be the main risk to continuing
in 2024, in a similar way to 2023 and lead to lower than expected crop yields.

By the last quarter of the year, La Niña is expected to begin, but it may take until the start of 2025 before the true La Niña conditions take over.

Australia

Farmers in Australia may not have a real sense of what El Niño actually is or how their country is really affected after experiencing other factors that contributed to record heat and drought in spring of 2023, followed by periods of heavy rainfall over the summer. While El Niño had formed in winter of 2023, its impact was masked by other global patterns, such as the Indian Ocean Dipole and the Southern Annular Mode – one of which brought the dry, hot conditions and the other helped bring the rain to eastern areas. The close proximity to Indonesia and the MJO (The Madden-Julian Oscillation) also had a big impact on climate volatility in the region by increasing tropical cyclones and rainfall across most areas, especially north and east.

Weather and Warm Sea Temperatures Impact on Australian Weather

Fig 4. While dry weather has returned in the short-term and likely will persist
through the fall and possibly into the winter, periods of heavier rainfall
will continue to be possible, due to the MJO (The Madden-Julian Oscillation)
and warm sea surface temperatures.

As the fall season is on the horizon, drier conditions have retaken the reins across much of the country. This is likely due to El Niño finally strengthening as all the other more regional weather patterns are weakening. Heading through fall into winter, the overall pattern will favor dry conditions with above normal temperatures.

There are two weather phenomena still at play that could bring periods of heavy rain and cooler temperatures to the region. One of those is the warmer than normal water in the Tasman Sea, which is what helped fuel the rain over the summer in the eastern regions. The other is the MJO. The MJO is currently in a weakened state, but it has been very active so far this year and a reemergence is likely in March. This will continue to be the biggest risk for rain and flooding through the rest of 2024.

In Conclusion

Due to climate change and changing global weather patterns, extreme weather events may cause people in some regions of the world to believe leap years and bad weather are connected. Scientifically, there is not a connection and leap years are not doomed for bad weather.

Looking for a more detailed and scientific forecast for this leap year or the leap years to come? Please reach out to our climate intelligence experts at ClimateAi.

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