Jay Grymes

The Louisiana climate is heavily influenced by the Gulf of Mexico and the subtropical climate that we share with the four other Gulf Coast states. Of those Gulf Coast states, we are on average the wettest. That rain is a big component of why we call Louisiana Sportsman's Paradise, and the abundance of water that creates a green environment is a monster contributor to Louisiana agriculture.

Given that it's a subtropical climate, Louisiana has a very long growing season compared to other parts of the country. That extended growing season coupled with abundant moisture is one of the reasons why forestry is our biggest agricultural sector. It's a wonderful environment for growing trees throughout the year.

In a normal year, we get a surplus amount of rain in the winter and spring. If it's not too excessive, that's a good thing. It sets up a good reservoir of summertime moisture. However, that surplus can also lead to significant flooding during the winter and spring seasons, and that can be devastating for agriculture, particularly in the northern half of the state.

In the summer months, the northern half of the state only averages about half as much rain as the southern part of the state. That explains the need for irrigation for the central and northern parishes. Under a normal annual pattern, this is a manageable and productive rainfall climatology for agriculture. Problems arise, however, when rainfall runs below normal for extended periods of time. Then, even “wet” Louisiana can slip into drought. Most recently, drought conditions developed two years ago, reaching critical levels by summer 2023. Not only was that devastating for a good bit of the state’s agriculture, but it also generated one of the worst wildfire seasons that the state has suffered in decades.

The moral of the story is that when we look at averages, Louisiana looks like a great agricultural state from a weather perspective. Typically, it is, but in recent years we have seen a higher-than-normal degree of year-to-year and intra-year rainfall variability — wet years followed by very dry years — and those flip-flops are unpredictable. More importantly, that variability can be a constraining and inhibiting factor for Louisiana agriculture.

Then there is the issue of tropical weather. While the focus of tropical storm and hurricane impacts tends to be on the coastal parishes, we can’t ignore the potential effects of tropical systems throughout the state. Tropical winds and rains of 10 to 20 inches can extend from the coast all the way through the northern parishes. What is a bit troubling is that the 21st century has seen the greatest frequency of tropical landfalls that Louisiana has ever experienced based on records back to the 1850s. That uptick in landfall activity has the state averaging more than one named-storm landfall every year since 2001.

In summary, Louisiana’s normal weather and climate patterns do a great job of supporting and sustaining the state’s wide variety of agriculture, forestry and aquaculture. However, producers need to be flexible with their management practices and adapt to future variability in rainfall, our key climatic driver. In addition, where possible, producers need to look at schemes that may reduce the impacts of increased tropical activity.

Whether you want to attribute recent climatic trends across the Bayou State to anthropogenic causes or not, it's clear that the state has experienced an increase in climate variability, if not climate change, over recent decades. Louisiana agriculture, and the state as a whole, must prepare for the possibility that this kind of variability may continue for at least the foreseeable future.

Jay Grymes is the interim state climatologist and chief meteorologist for WAFB-TV in Baton Rouge. As state climatologist, Grymes is partnering with the LSU AgCenter to provide information, education and outreach.

This article appears in the spring 2024 edition of Louisiana Agriculture.

Jay Grymes was named the interim Louisiana state climatologist in February. Grymes, the chief meteorologist for WAFB in Baton Rouge, previously served as the state climatologist from 1991 to 2003. Photo by Olivia McClure