The Southwest U.S. is mired in an ever-worsening drought, one that has left deer starving in Hawaii, turned parts of the Rio Grande into a wading pool, and set a record in Colorado for the most days of “exceptional drought.”
People around the world know San Diego for its beautiful, sunny, and mild weather. San Diego residents know our daily weather has more variety than visitors might imagine.
Climate is defined as the average weather conditions in an area over a long period, generally 30 years or more. German climate scientist Wladimir Koppen first divided the world’s climate into six regions in the early 1900s.
The world’s oceans reached their hottest level in recorded history in 2020, supercharging the extreme weather impacts of the climate emergency, scientists have reported.
More than 90% of the heat trapped by carbon emissions is absorbed by the oceans, making their warmth an undeniable signal of the accelerating crisis. The researchers found the five hottest years in the oceans had occurred since 2015, and that the rate of heating since 1986 was eight times higher than that from 1960-85.
In 2020, Californians endured the hottest August, September and October since 1895. Climate scientists warn the trends are evidence of a warming planet. Rising temperatures combined with less rain and high winds have worsened the chance of extreme fire weather.
People around the world know San Diego for its beautiful, sunny, and mild weather. San Diego residents know our daily weather has more variety than visitors might imagine.
Climate is defined as the average weather conditions in an area over a long period, generally 30 years or more. German climate scientist Wladimir Koppen first divided the world’s climate into six regions in the early 1900s.
Since then, U.S. climate zones have been defined in more detail. The U.S. Department of Agriculture defines climate zones according to the lowest average temperature in the region. You may also be familiar with the 24 climate zones identified in Sunset Magazine’s iconic Sunset Western Garden Book. The book is now out of print, but is available online as an interactive edition. Existing print copies from the last edition printed in 2012 are prized heirlooms.
Devoted gardeners still follow the 24 climate zones featured in the guide. This is based on the California Irrigation Management Information System (CIMIS) adoption of a similar map identifying 24 climate zones.
San Diego County’s geography falls within six of the 24 CIMIS climate zones. Photo: CIMIS
Depending on the amount of rainfall, temperature, humidity, wind, shade, and the nature of the soil, water in the ground evaporates at different rates. When evaporation is higher, the soil becomes dry more quickly.
Evapotranspiration (ET) is the process by which water is transferred from the land to the atmosphere by evaporation from the soil and other surfaces, and by transpiration from plants.
Reference Evapotranspiration (ETo) is a baseline formula. All your plant water needs are measured against this baseline in a complex series of measurements and calculations.
In metropolitan San Diego County, our annual ETo rate increases as you move inland, meaning the soil becomes dry more quickly.
Fortunately, we don’t need to worry about making these calculations on our own. CIMIS maintains a statewide system of weather stations and reference plots. From these, it has identified the six main ET Zones in San Diego County.
Understanding your ETo zone and gardening climate zone are important first steps toward deciding how much water your landscaping will need. Working against the ETo and gardening climate zones can greatly increase your need for irrigation.
Learn more about your ETo climate zone’s specifics and gardening microclimate on the California Irrigation Management Information System website.
This article is part of a year-long series inspired by the 71-page Sustainable Landscapes Program guidebook available at SustainableLandscapesSD.org. The Water Authority and its partners also offer other great resources for landscaping upgrades, including free WaterSmart classes at WaterSmartSD.org.
Colorado is no stranger to drought. The current one is closing in on 20 years, and a rainy or snowy season here and there won’t change the trajectory. This is what climate change has brought. “Aridification” is what Bradley Udall formally calls the situation in the western U.S. But perhaps more accurately, he calls it hot drought – heat-induced lack of water due to climate change. That was the core of research released in 2017 by Udall, a senior climate and water scientist at Colorado State University’s Colorado Water Center, and Jonathan Overpeck at the University of Michigan.
Increasingly strong storms are responsible for more than a third of the nation’s flood costs, swelling the tab by billions of dollars a year as climate change continues to fuel more extreme weather, according to new research at Stanford University.
Increased precipitation resulting partially from climate change has caused an additional $2.5 billion a year in U.S. flood damage, according to a new study that pinpoints the effect of changing weather on the cost of natural disasters.
Buried in San Diego County’s lagoons are centuries worth of carbon, cached in muddy stockpiles that scientists say could help combat climate change. Recently, scientists with the conservation organization Wildcoast and Scripps Institution of Oceanography started studying how much carbon coastal wetlands can capture, and how to restore these environments to boost that capacity.
December through February is historically when some of the biggest weather systems arrive in Northern California with big rain and snow totals. While March can also be a big snow month, the window of opportunity for big rain and snow totals starts to narrow.
Now, long range outlooks are calling for a week and half long stretch of unseasonably dry and warm weather.
The Water News Network is San Diego County’s source for water news and information.
