Weather on May 21
Boise, ID
55 Years of Data
Avg High
71°F
Avg Low
46°F
Warmest
2023
77°F avg
Coldest
1986
46°F avg
About This Date
May 21st in Boise, ID typically brings pleasant spring weather, with average highs around 71°F and lows near 46°F — a 25°F daily swing. Over 55 years of records, the warmest May 21st was in 2023 (77°F average), while the coldest was 1986 (46°F) — a 31°F range across recorded history. Rain or other precipitation has occurred on about 33% of May 21st dates historically, with the wettest May 21st recording 2.03" of rain. Temperatures on this date have remained relatively stable over the past several decades.
Temperatures on this date have remained relatively stable over the past several decades.
Planning for May 21st in Boise, ID? Great weather for outdoor activities. Consider bringing rain gear or an umbrella.
| Year | High | Low | Avg | Precip | Snow |
|---|---|---|---|---|---|
| 2025 | 70° | 40° | 55° | — | — |
| 2024 | 69° | 39° | 54° | — | — |
| 2023warmest | 91° | 62° | 77° | 0.08" | — |
| 2022 | 68° | 42° | 55° | — | — |
| 2021 | 55° | 42° | 49° | 0.08" | — |
| 2020 | 60° | 46° | 53° | 0.28" | — |
| 2019 | 60° | 45° | 52° | 1.7" | — |
| 2018 | 78° | 54° | 66° | — | — |
| 2017 | 75° | 49° | 62° | — | — |
| 2016 | 58° | 46° | 52° | 0.13" | — |
| 2015 | 73° | 52° | 62° | 0.08" | — |
| 2014 | 76° | 50° | 63° | 0.15" | — |
| 2013 | 85° | 52° | 68° | — | — |
| 2012 | 87° | 63° | 75° | — | — |
| 2011 | 74° | 48° | 61° | — | — |
| 2010 | 58° | 37° | 47° | 0.03" | — |
| 2009 | 78° | 42° | 60° | — | — |
| 2008 | 59° | 42° | 51° | — | — |
| 2007 | 57° | 43° | 50° | 0.03" | — |
| 2006 | 82° | 55° | 69° | 0.18" | — |
| 2005 | 68° | 41° | 55° | — | — |
| 2004 | 68° | 51° | 60° | 0.1" | — |
| 2003 | 76° | 48° | 62° | — | — |
| 2002 | 59° | 44° | 52° | 0.03" | — |
| 2001 | 74° | 37° | 55° | — | — |
| 2000 | 87° | 53° | 70° | — | — |
| 1999 | 76° | 48° | 62° | — | — |
| 1998 | 56° | 42° | 49° | 2.03" | — |
| 1997 | 81° | 44° | 62° | — | — |
| 1996 | 65° | 48° | 56° | 0.05" | — |
| 1995 | 77° | 46° | 62° | — | — |
| 1994 | 73° | 46° | 60° | — | — |
| 1993 | 74° | 55° | 64° | — | — |
| 1992 | 71° | 43° | 57° | — | — |
| 1991 | 75° | 42° | 59° | — | — |
| 1990 | 72° | 51° | 61° | — | — |
| 1989 | 76° | 43° | 59° | — | — |
| 1988 | 87° | 50° | 69° | — | — |
| 1987 | 67° | 36° | 51° | — | — |
| 1986coldest | 56° | 37° | 46° | 0.13" | — |
| 1985 | 73° | 47° | 60° | — | — |
| 1984 | 58° | 41° | 49° | — | — |
| 1983 | 72° | 44° | 58° | — | — |
| 1982 | 80° | 48° | 64° | — | — |
| 1981 | 62° | 48° | 55° | 0.15" | — |
| 1980 | 90° | 62° | 76° | 0.13" | — |
| 1979 | 82° | 49° | 65° | — | — |
| 1978 | 82° | 49° | 65° | — | — |
| 1977 | 74° | 48° | 61° | — | — |
| 1976 | 76° | 39° | 57° | — | — |
| 1975 | 66° | 50° | 58° | — | — |
| 1974 | 68° | 33° | 51° | — | — |
| 1973 | 70° | 34° | 52° | — | — |
| 1972 | 54° | 44° | 49° | 0.46" | — |
| 1971 | 68° | 45° | 56° | — | — |
55 years of data from BOISE AIR TERMINAL