MU Extension Offers Free Frost/Freeze Guide

Mar 08, 2018

By Linda Geist

The free online Missouri Frost/Freeze Probabilities Guide helps farmers and gardeners make planting decisions.

University of Missouri Extension integrated pest management specialists created the website at ipm.missouri.edu/FrostFreezeGuide(opens in new window). The guide is also available as a free downloadable PDF at extension.missouri.edu/IPM1033(opens in new window).

Both provide frost and freeze probabilities, tables, maps and dates for the 103 National Weather Service cooperative weather stations in Missouri, said MU Extension climatologist Pat Guinan.

The National Centers for Environmental Information(opens in new window) provides information based on data for 1981-2010.

The Missouri growing season typically runs from April to October. Where you live in Missouri makes a big difference in when the first or last freeze occurs, said Guinan.

Climatologists can predict frost timing based on temperature records and the region’s topography.

The median date maps provide the last spring and first fall median frost/freeze dates for specific temperature thresholds. In this guide, climatologists define the median date as the date when there is a 50 percent chance a frost or freeze temperature will occur before or after a given date.

Extreme date maps give the latest spring and earliest fall frost and freeze dates using weather stations with more than 100 years of temperature observations.

The weather station map and probabilities table show data and probability thresholds for weather stations across the state. You can search for the location nearest you by using the weather station search tool, Guinan said.

Source: missouri.edu

Video: Spring 2026 weather outlook for Wisconsin; What an early-arriving El Niño could mean

Northeast Wisconsin is a small corner of the world, but our weather is still affected by what happens across the globe.

That includes in the equatorial Pacific, where changes between El Niño and La Niña play a role in the weather here -- and boy, have there been some abrupt changes as of late.

El Niño and La Niña are the two phases of what is collectively known as the El Niño Southern Oscillation, or ENSO for short. These are the swings back and forth from unusually warm to unusually cold sea surface temperatures in the Pacific Ocean along the equator.

Since this past September, we have been in a weak La Niña, which means water temperatures near the Eastern Pacific equator have been cooler than usual. That's where we're at right now.

Even last fall, the long-term outlook suggested a return to neutral conditions by spring and potentially El Niño conditions by summer.

But there are some signs this may be happening faster than usual, which could accelerate the onset of El Niño.

Over the last few weeks, unusually strong bursts of westerly winds farther west in the Pacific -- where sea surface temperatures are warmer than average -- have been observed. There is a chance that this could accelerate the warming of those eastern Pacific waters and potentially push us into El Niño sooner than usual.

If we do enter El Nino by spring -- which we'll define as the period of March, April and May -- there are some long-term correlations with our weather here in Northeast Wisconsin.

Looking at a map of anomalously warm weather, most of the upper Great Lakes doesn't show a strong correlation, but in general, the northern tiers of the United States do tend to lean to that direction.

The stronger correlation is with precipitation. El Niño conditions in spring have historically come with a higher risk of very dry weather over that time frame, so this will definitely be a transition we'll have to watch closely as we move out of winter.