43.567°N, 116.241°W · station BOIthr · 1875–2026 · 152 years of record
The Almanac Ribbon
Every day of the year at Boise: the record high and record low ever set (outer lines), the everyday normal range (shaded band), and the full record envelope behind it.
Record highRecord lowNormal high–low band (1991–2020)hottest ever 111°F · coldest ever -28°F
Records by Month
Month
Record high
Record low
Jan
66°Jan 31, 2024
-28°Jan 16, 1888
Feb
71°Feb 29, 1992
-15°Feb 5, 1989
Mar
83°Mar 20, 2026
5°Mar 13, 1906
Apr
92°Apr 26, 1898
11°Apr 1, 1936
May
100°May 29, 1897
22°May 5, 1982
Jun
110°Jun 28, 2015
30°Jun 5, 1901
Jul
111°Jul 12, 1898
35°Jul 5, 1986
Aug
110°Aug 4, 1961
32°Aug 25, 1892
Sep
104°Sep 7, 2022
23°Sep 24, 1926
Oct
94°Oct 1, 1992
11°Oct 29, 1971
Nov
78°Nov 6, 1999
-10°Nov 28, 1896
Dec
70°Dec 10, 1939
-25°Dec 22, 1990
All-time
111°Jul 12, 1898
-28°Jan 16, 1888
Longest-Standing Records
The daily records that have held the longest — set in the earliest years and never beaten since. Highs power Boise on hottestsince.com; lows on coldestsince.com.
Oldest-standing record highs
Date
Record
Set
Standing
Apr 13
86°
1875
151yrs
Apr 14
90°
1875
151yrs
Apr 15
86°
1875
151yrs
Apr 16
86°
1875
151yrs
Apr 21
90°
1875
151yrs
Sep 17
98°
1875
151yrs
Dec 3
61°
1875
151yrs
Dec 7
62°
1875
151yrs
Dec 8
60°
1875
151yrs
Feb 14
65°
1876
150yrs
May 9
92°
1876
150yrs
Jun 18
107°
1876
150yrs
Oldest-standing record lows
Date
Record
Set
Standing
Oct 2
28°
1877
149yrs
Oct 25
19°
1878
148yrs
Mar 13
10°
1880
146yrs
Jul 11
41°
1880
146yrs
Oct 11
25°
1880
146yrs
Jun 27
36°
1881
145yrs
Jul 31
42°
1881
145yrs
Aug 28
39°
1881
145yrs
Sep 27
30°
1881
145yrs
Feb 18
0°
1882
144yrs
Feb 19
-5°
1882
144yrs
Mar 5
10°
1882
144yrs
All-Time Extremes
Hottest ever
111°F
1898-07-12
Coldest ever
-28°F
1888-01-16
Longest heat streak
50 days
≥ 90°F · ended 1875-08-22
The Warming Trend
Boise's annual mean temperature, each year a stripe — blue below the 1991–2020 average, red above.
Days Above / Below the Mark
58 days ≥90°F in 2026 · normal 46 · record 76 in 1875
48 days ≤32°F in 2026 · normal 115 · record 162 in 1985
The Full Record
Every day of the year, record and normal high & low with the year each record was set. Type to filter, click a column to sort.