Idaho Climate Data
This StoryMap provides a summary of climate projections for the state of Idaho provided by ClimRR, the Climate Risk and Resilience Portal.
Background for the HMP
In the maps below you will find data that is available for the entire continental United States via ClimRR, the Climate Risk and Resilience Portal. ClimRR provides peer-reviewed climate datasets in a nontechnical format and puts high-resolution, forward-looking climate insights into the hands of those who need them most. Community leaders and public safety officials can now understand how changing climate risks will affect the populations they serve. Access to this information will assist leaders as they strategically invest in infrastructure and response capabilities to protect communities for future generations. ClimRR has been made publicly available at no cost by Argonne, AT&T, and FEMA in order to enable greater climate resilience among local communities. ClimRR currently has climate projection maps available for temperature precipitation, winds, and fire weather. Argonne expects to add both coastal and inland flood projections, as well as other climate impacts and analytical capabilities to the tool in the coming months.
Introduction
The maps included here specifically spotlight climate projections for the state of Idaho and only show a subset of the available maps provided in ClimRR. All data presented here has been modeled by dynamically downscaling an ensemble of three separate global climate models using the Weather Research and Forecasting model (WRF), which is a regional climate model of North America. In order to more easily digest the maps, it will be helpful to provide a few definitions and clarifications:
- RCP4.5 represents a scenario in which human GHG emissions peak around 2040, then decline.
- RCP8.5 represents a worst-case scenario in which human GHG emissions continue to rise throughout the 21st century.
- Historical maps are also the result of climate modelling. They do not reflect actual recorded values from the past but rather the model outputs when historic GHG emission values are used as inputs.
- Timeframes:
- Historical/Baseline: 1995-2004
- Mid-Century: 2045-2054
- End-Century: 2085-2094
A Note on Incorporating Equity
ClimRR is designed to be interactive with FEMA's Resilience Analysis and Planning Tool (RAPT) to provide local data on social vulnerability and community characteristics. RAPT includes geospatial information system (GIS) data layers of community characteristics that represent potential challenges to disaster resilience, important data layers for equity considerations, and community infrastructure locations and characteristics. For example, users could focus planning efforts on communities most vulnerable to the impacts of extreme heat events by viewing projections of high temperatures in the future alongside community data on populations with disabilities or those that are medically dependent on electricity.
Temperature
Annual Max Daily Temperatures
Summary
The annual max daily temperature projections can be thought of as average daily highs. This set of maps demonstrates the annual temperature increases that the state of Idaho will experience throughout the century under the two different climate scenarios. It demonstrates how and where the overall temperature will vary across the state. This is a good summary of overall changes in high temperatures throughout the year, but the later layers may give greater insight for how this manifests in seasonal changes and affects hazard mitigation.
Modeled Historical Annual Max Daily Temperature
Historical | RCP4.5 Mid-Century
Pull the slider bar to the right to fully view a map of the modeled historical annual max daily temperatures. Pull the slider bar to the left to fully view a map of the RCP4.5 mid-century annual max daily temperatures.
Historical | RCP4.5 End-Century
Pull the slider bar to the right to fully view a map of the modeled historical annual max daily temperatures. Pull the slider bar to the left to fully view a map of the RCP4.5 end-century annual max daily temperatures.
Historical | RCP8.5 Mid-Century
Pull the slider bar to the right to fully view a map of the modeled historical annual max daily temperatures. Pull the slider bar to the left to fully view a map of the RCP8.5 mid-century annual max daily temperatures.
Historical | RCP8.5 End-Century
Pull the slider bar to the right to fully view a map of the modeled historical annual max daily temperatures. Pull the slider bar to the left to fully view a map of the RCP8.5 end-century annual max daily temperatures.
RCP4.5 Mid-Century | RCP8.5 Mid-Century
Pull the slider bar to the right to fully view a map of the RCP4.5 mid-century annual max daily temperatures. Pull the slider bar to the left to fully view a map of the RCP8.5 mid-century annual max daily temperatures.
RCP4.5 End-Century | RCP8.5 End-Century
Pull the slider bar to the right to fully view a map of the RCP4.5 end-century annual max daily temperatures. Pull the slider bar to the left to fully view a map of the RCP8.5 end-century annual max daily temperatures.
Summer Max Daily Temperatures
Summary
Under the RCP8.5 scenario at mid-century, the summer average daily highs are predicted to surpass 90 degrees in most of the Southwestern and Central regions of the state, particularly along the Snake River Plain, and portions of the southeastern as well. And the panhandle, will see average summer highs going up by five degrees or more by mid-century. This trend indicates that the southern region of the state overall, as well as some isolated regions in the panhandle such as Nez Perce County, may need greater resources and attention offered to populations with greater risk of being exposed to the heat or experiencing heat-related illness in these conditions. This could include unhoused and elderly populations.
Historical | RCP 8.5 Mid-Century
Pull the slider bar to the right to fully view a map of the modeled historical summer max daily temperatures. Pull the slider bar to the left to fully view a map of the RCP8.5 mid-century summer max daily temperatures.
Historical | RCP 8.5 End-Century
Pull the slider bar to the right to fully view a map of the modeled historical summer max daily temperatures. Pull the slider bar to the left to fully view a map of the RCP8.5 end-century summer max daily temperatures.
Winter Minimum Daily Temperatures
Overview
The annual minimum daily temperatures can be thought of as projections of average daily lows. The winter average daily lows maps demonstrate that by mid-century under the RCP8.5 scenario, we will see a growing region of Southwestern Idaho that will no longer have average lows below 30 degrees. This could drastically impact snowpack retention and thus drought and wildfire conditions in the summer and fall. We will discuss each of these topics in more detail below.
Historical | RCP 8.5 Mid-Century
Pull the slider bar to the right to fully view a map of the modeled historical winter minimum daily temperatures. Pull the slider bar to the left to fully view a map of the RCP8.5 mid-century winter minimum daily temperatures.
Historical | RCP 8.5 End-Century
Pull the slider bar to the right to fully view a map of the modeled historical winter minimum daily temperatures. Pull the slider bar to the left to fully view a map of the RCP8.5 end-century winter minimum daily temperatures.
Fire Weather Index
Overview
The ClimRR data available for fire projections are based on several climate-related factors, which are aggregated to calculate a Fire Weather Index (FWI). FWI values signal different levels of relative fire danger across regions. Values above 25 typically represent a high level of danger in the northern regions, whereas values above 40-45 often represent a high level of danger in the Southwest. It is important to note that while FWI incorporates numerous factors that are conducive to greater fire risk, it does not include information about fuel types or the results of fire behavior models. For more information on the meaning of the Fire Weather Index (FWI), please visit the Canadian Wildland Fire Information System's page describing this index: https://cwfis.cfs.nrcan.gc.ca/background/summary/fwi.
Because Idaho is in the northern region of the United States, a FWI value over 25 is taken to typically represent a high level of danger. Anything code as yellow, orange, or red in the maps below falls above this 25 threshold, with relative danger growing more pronounced from yellow to red. In the maps below, we can see that the FWI index is predicted to increase for much of the state by mid-century and even more so by end-of-century.
In the historical model, the Median FWI for the state is 20.2. This number will increase modestly by mid-century to 20.7 and then will see a much greater increase to 25.4 by end-of-century. This means that the majority of the state will fall above our typical threshold of 25 for a high level of fire danger by the 2085-2094 period.
Historical | RCP 8.5 Mid-Century
Pull the slider bar to the right to fully view a map of the modeled historical summer fire weather index values. Pull the slider bar to the left to fully view a map of the RCP8.5 mid-century summer fire weather index values.
Historical | RCP 8.5 End-Century
Pull the slider bar to the right to fully view a map of the modeled historical summer fire weather index values. Pull the slider bar to the left to fully view a map of the RCP8.5 end-century summer fire weather index values.
Precipitation
Change in Annual Precipitation
Overview
The precipitation data summarized in the figures below demonstrates the projected changes in precipitation across Idaho. Under the RCP4.5 scenario at mid-century, Idaho is likely to experience similar amounts of rain as it does currently with maximum increases of 2-4 inches per year coming in the northern regions and the Boise area and some areas of eastern Idaho seeing a decrease in precipitation. Meanwhile at mid-century under the RCP8.5 scenario, the annual increase in precipitation is projected to be more widespread and marginally more pronounced with most of the western and northern regions seeing an increase of 2-4 inches and some areas of the panhandle exceeding this.
By end-of-century however, this relationship inverts. With the RCP8.5 scenario bringing most of Idaho a 4-6 inch per year increase in rain whereas the RCP4.5 scenario will bring more than a 10-inch per year increase in precipitation to the northern regions of the state as well as the area just to the northwest of Boise.
Historical vs. RCP4.5 Mid-Century
This map displays the difference between modeled historical and RCP4.5 mid-century annual precipitation values.
Historical vs. RCP4.5 End-Century
This map displays the difference between modeled historical and RCP4.5 end-century annual precipitation values.
Historical vs. RCP8.5 Mid-Century
This map displays the difference between modeled historical and RCP8.5 mid-century annual precipitation values.
Historical vs. RCP8.5 End-Century
This map displays the difference between modeled historical and RCP8.5 end-century annual precipitation values.
Winter Maximum Daily Precipitation
Overview
In alignment with annual precipitation, the RCP8.5 winter maximum daily precipitation will increase at mid-century especially at the base of the Idaho panhandle. Yet unlike the RCP8.5 annual totals, the model predicts that Idaho will continue to see increases in maximum daily precipitation by the end of the century under this scenario on a seasonal basis. It is important to note that the maximum daily precipitation value will only increase from 2.2 to 2.6 at mid-century and 2.8 at end-of-century. However, the way this precipitation will change spatially across the state is more noteworthy. We see that the historical model only saw isolated regions to the northeast of Boise and the base of the Idaho panhandle exceeding 2 inches. The portion of the state over this threshold in the historical model was only 1.6%, whereas by mid-century 3.5% will fall in this category and 7.4% by end-of-century. Note also that the precipitation values presented throughout this report are in inches of water equivalent in cases where precipitation may take the form of snow (see Footnote).
Historical | RCP8.5 Mid-Century
Pull the slider bar to the right to fully view a map of the modeled historical winter maximum daily precipitation. Pull the slider bar to the left to fully view a map of the RCP8.5 mid-century winter maximum daily precipitation.
Historical | RCP8.5 End-Century
Pull the slider bar to the right to fully view a map of the modeled historical winter maximum daily precipitation. Pull the slider bar to the left to fully view a map of the RCP8.5 end-century winter maximum daily precipitation.
Note: These measurements are presented in liquid equivalents, so the depth of snow that these maximum daily values will equate to depends on the density of the snow. For freshly fallen snow in the U.S. on average, one foot of snow roughly equates to one inch of water. This means that the threshold of 2 inches of water used above would equate to two feet of snowfall in a single day.
Consecutive Days with No Precipitation (Decadal Maximum)
Overview
The maps below demonstrate the change in maximum consecutive number of days that Idaho is projected to go without precipitation as modeled for historical, mid-century, and end-of-century. This can be thought of as the change in length of dry periods between precipitation events. In the historical model, this maximum has a median value of 26.7 days with 34% of the state experiencing maximum dry spells equal to or greater than 30 days in length. Under the RCP4.5 scenario, these data points will increase to 29.3 days and 44% respectively by midcentury and 32.3 days and 64% by end-of-century. Alternatively under the RCP8.5 scenario, these same data points will be 28.3 days and 42% at mid-century and 25 days and 30% at end-of-century.
Historical | RCP4.5 Mid-Century
Pull the slider bar to the right to fully view a map of the modeled historical max consecutive days with no precipitation. Pull the slider bar to the left to fully view a map of the RCP4.5 mid-century max consecutive days with no precipitation.
Historical | RCP4.5 End-Century
Pull the slider bar to the right to fully view a map of the modeled historical max consecutive days with no precipitation. Pull the slider bar to the left to fully view a map of the RCP4.5 end-century max consecutive days with no precipitation.
Historical | RCP8.5 Mid-Century
Pull the slider bar to the right to fully view a map of the modeled historical max consecutive days with no precipitation. Pull the slider bar to the left to fully view a map of the RCP8.5 mid-century max consecutive days with no precipitation.
Historical | RCP8.5 End-Century
Pull the slider bar to the right to fully view a map of the modeled historical max consecutive days with no precipitation. Pull the slider bar to the left to fully view a map of the RCP8.5 end-century max consecutive days with no precipitation.
Possibility for Meaning Making from These Maps
When these consecutive days without precipitation maps are coupled with the projections for annual precipitation, we can begin to see a clearer picture of how Idaho will experience precipitation under RCP4.5 and RCP8.5 into the future.
Under the RCP8.5 scenario, Idaho is projected to see a general increase in both annual precipitation and maximum consecutive days without precipitation by mid-century. This suggests that precipitation events under this scenario will occur less frequently but occur with a greater magnitude or intensity. Then by end-of-century, this scenario is projected to see a total increase from historical to end-of-century of no more than 6 inches per year and widespread increases of only 2-4 inches per year while the maximum consecutive days with no precipitation will actually decrease from mid-century. Thus, Idaho will be finishing out the century under this scenario with a widespread but more moderately elevated amount of annual precipitation that is likely to fall more consistently.
Under the RCP8.5 scenario, Idaho is projected to see a general increase in both annual precipitation and maximum consecutive days without precipitation by mid-century. This suggests that precipitation events under this scenario will occur less frequently but occur with a greater magnitude or intensity. Then by end-of-century, this scenario is projected to see a total increase from historical to end-of-century of no more than 6 inches per year and widespread increases of only 2-4 inches per year while the maximum consecutive days with no precipitation will actually decrease from mid-century. Thus, Idaho will be finishing out the century under this scenario with a widespread but more moderately elevated amount of annual precipitation that is likely to fall more consistently.
This precipitation analysis highlights the importance of downscaled climate modelling offered for multiple time horizons and scenarios. It helps illustrate the highly-localized and oftentimes unexpected ways that climate will impact regions across a state, and underscores the importance of such localized analysis over more generalized state-wide or nation-wide trends.
Explore More Map Layers Directly on ClimRR
Although the maps above are limited to within the state boundaries of Idaho, many important systems—from communities and metropolitan areas to rivers and watersheds—that affect Idaho communities extend beyond state borders. Therefore, climate projections in the region surrounding Idaho could also impact the social, economic, and environmental landscape of the state. Exploring the nation-wide climate projections on ClimRR may provide additional context for Idaho’s hazard planning activities.
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