WHAT ARE PHENO FORECASTS?

Pheno Forecast maps predict key life cycle stages in invasive and pest species, to improve management efficacy.  For insect pest species, Pheno Forecasts are based on published growing degree day (GDD) thresholds for key points in species life cycles. These key points typically represent life cycle stages when management actions are most effective. These maps are updated daily and available 6 days in the future.

Help us improve these maps! Our Pheno Forecast map products are still in development, and we seek input on their performance in your area. Give your feedback at the bottom of the page.

SIGN UP FOR PHENO FORECAST NOTIFICATIONS!

Sign up to be notified by email approximately two weeks and again six days ahead of key growing degree day thresholds for species of interest at your location

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Nature’s Notebook data reveal how climate impacts flowering in eastern redbud trees

Sat, Jul 25, 2026
Publication Summary

The appearance of bright pink flowers on eastern redbud trees is a reliable indicator that spring has arrived in the eastern U.S. However, the timing varies across the species’ range and not much is understood about the climate conditions that trigger flowering. A team of researchers used Nature’s Notebook observations from more than 150 sites across the eastern U.S. to identify how temperatures and daylength influence flowering in eastern redbuds. They used a novel modeling approach to show that both the amount of cold in winter and warmth in spring are important. However, the relative amount of cold and warmth needed to trigger flowering differed among sites. Trees in the north needed more cold and less heat to flower than trees in the south. Using these results, researchers can make accurate predictions about redbud flowering given recent climate conditions and better understand the potential impacts of climate change.

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Join us at Botany 2026 in Tucson!

Thu, Jul 09, 2026
News

Are you attending the Botany Meeting in Tucson this August 1-5? We'll see you there! Come meet USA-NPN staff and students at our booth and talk to us about our new Nature's Notebook app (due out later this summer), the phenology data we have available, how to implement phenology monitoring with your undergraduate class or at your organization, and more!

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Weather impacts autumn phenology differently in the eastern and western U.S.

Mon, May 04, 2026
Publication Summary

The timing of phenological events in autumn like leaf color and leaf fall have important consequences for nutrient cycling, species interactions, and even tourism. However, there has been less research on autumn phenology than spring phenology and the effects of temperature, precipitation, and day length are not well understood. To fill this gap, researchers used Nature’s Notebook observations of autumn phenology from woody plant species across the U.S. They found strong regional differences. Leaf color in the eastern U.S. was driven primary by summer temperatures, whereas in the western U.S., leaf color change was influenced more strongly by precipitation that occurred more than six months prior. Given these differences, the effects of climate change are likely to be complex. Increased temperatures may extend the growing season for some plants and increased drought may shorten the growing season for others.

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Late Bloom Index is live!

Fri, Apr 17, 2026
Seasonal Story

We are excited to unveil another new index of spring – the Late Bloom Index! The Late Bloom Index indicates when plants that bloom at the tail end of the season are flowering, effectively representing the end of the spring season.

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Introducing the Thermal Calendars tool

Mon, Mar 09, 2026
News

Temperature is an important factor governing when seasonal events happen in many plant and animal species. For many species, events like leaf-out, flowering, and egg hatch are triggered when a specific amount of heat has accumulated since the start of the year. We typically measure accumulated heat in growing degree days (GDDs). The Thermal Calendars tool indicates when particular GDD levels (or thresholds) of accumulated warmth are met each year in the northeastern U.S. Local resource managers can use the tool to determine when problematic insect pests are expected to enter particular life stages when they may cause the most damage or are most readily controlled.

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Nature’s Notebook observations reveal clear changes in New Jersey

Mon, Mar 09, 2026
Publication Summary

Global temperatures are increasing and the impacts are numerous and wide ranging. Temperatures have been rising at a particularly fast rate in the northeastern U.S., including many densely populated areas like New Jersey. To document environmental changes and better understand the impacts of climate change in this region since the mid-1960s, researchers gathered data on sea and air temperatures, lake ice, and snowfall. They complimented the weather data with observations of spring leaf-out and flowering in local lilac plants. The researchers found clear evidence of climate change, with notable increases in both daytime and nighttime temperatures and earlier spring plant activity. These changes will have numerous economic, social, and ecological impacts. Among other effects, earlier spring onset has the potential to alter plant-pollinator interactions and the length of the pollen and growing seasons.

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Phenology Week! March 16-20, 2026

Tue, Feb 03, 2026
News

March 16-20, 2026 is Phenology Week - a virtual celebration of the seasonal cycles of plants and animals. The purpose of Phenology Week is to celebrate YOU, our Nature's Notebook observers, Local Phenology Programs, and partners! We'll have webinars, awards, daily challenges, observer stories, and more.

We want to hear from you! What did you enjoy about Phenology Week this year, what could be improved, what do you want to see next year? 

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