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Record deep dive

Stanley has more
summer-like days

Climate Central's 2025 Lingering Summer Heat analysis used ACIS temperature data to measure how the final summer-like day changed from 1970 to 2024. We applied that same method to the Stanley ACIS station record.(1)

What Climate Central did

In its 2025 Lingering Summer Heat study, Climate Central used local daily maximum temperatures from the Applied Climate Information System for 1970-2024.(1, 2)

  1. For each location, they found the annual last date when the daily high was greater than or equal to that location's historical summer-like temperature.
  2. They defined historical summer-like temperature as the 75th percentile of daily high temperatures during 1991-2020, rounded to the nearest 5 deg F.
  3. They calculated the long-term change in that last date with a 1970-2024 linear trend.

Stanley calculation

For Stanley, the 1991-2020 75th-percentile daily high is 72 deg F, which rounds to 70 deg F. Using ACIS years with enough daily temperature records from 1970-2024, the trend line moves the final summer-like day about 5 days later.

70 deg FStanley summer-like threshold
5 days laterFinal summer-like day
39Years in trend

Last summer-like day by year

Each dot is one Stanley ACIS year with enough daily temperature records. The red line is the linear trend for the annual last date at or above 70 deg F.

Summer-like days per year

This is a second Stanley calculation using the same 70 deg F summer-like threshold. Instead of asking when the last summer-like day happened, it counts how many days in each year with enough daily temperature records reached 70 deg F or warmer. The 25 more days figure is the change over the full 1970-2024 trend, equal to about 4.7 more days per decade; it is not 25 more days every year.

25 more summer-like days a year

An increase of 4.7 more days per decade

Bars count days in each year with enough daily temperature records that reached 70 deg F or warmer. The red line is the linear trend for the count.

NOAA/ACIS COOP Station 108676 - Stanley, Idaho - ACIS exact station 108676 2 - temperature years with enough daily records only.

ACIS is used here as the exact Stanley daily climate station record.

Idaho information: the NOAA Idaho State Climate Summary reports statewide warming since the early 20th century and projects more intense heat waves. The Stanley calculations on this page use the Stanley ACIS station record, not a statewide average.(3)

Citations

  1. Climate Central. 2025. “Lingering Summer Heat.” Climate Matters, September 10, 2025.
  2. NOAA Regional Climate Centers. n.d. “Applied Climate Information System.” Accessed June 30, 2026.
  3. Runkle, J., K. E. Kunkel, R. Frankson, S. M. Champion, L. E. Stevens, and J. Abatzoglou. 2022. “Idaho State Climate Summary 2022.” NOAA Technical Report NESDIS 150-ID.