Drought in Cassia County, ID: 6.5 years in 10 since 2000

6.5 years in 10

Cassia County, ID: 17 of 26 full years had 13+ weeks in drought. More drought-prone than most US counties.

20002025

Drought years: 2000 (16 wk), 2001 (46 wk), 2002 (53 wk), 2003 (52 wk), 2004 (52 wk), 2005 (44 wk), 2007 (35 wk), 2008 (53 wk), 2009 (17 wk), 2012 (19 wk), 2013 (31 wk), 2014 (52 wk), 2015 (23 wk), 2018 (22 wk), 2021 (48 wk), 2022 (52 wk) and 2025 (27 wk). Not a single drought week in 2006, 2010, 2011, 2016, 2017, 2020 and 2024.

Plan for drought as normal: shrink the lawn, go drip and natives

Drought is the normal state of things here. Most of the yard goes to natives and gravel on drip; any grass that stays is a small, tough patch.

If you are replacing turf, plant natives in fall so roots set before the Sep peak, and check your water utility for a turf-removal rebate before you dig.

Against the rest of ID

5th most drought-prone of 44 ID counties; the ID middle is 5.8 in 10. Closest on the list: Jefferson County (6.5 in 10) and Franklin County (6.5 in 10). Driest in ID: Blaine County (6.5 in 10). Least drought: Kootenai County (4.2 in 10).

When in the year it hits

Most often in Sep (60% of weeks), then Oct (58%) and Aug (56%). Least in May (40%). May to September averages 51%.

47 Jan
50 Feb
47 Mar
47 Apr
40 May
45 Jun
53 Jul
56 Aug
60 Sep
58 Oct
51 Nov
50 Dec

The worst year: 2003

2003: 52 weeks in drought, peaking at D4 exceptional. Across 1,401 weekly maps: 50.4% of all weeks at D1 or worse, 29.6% at D2, 13.1% at D3, 115 weeks with some of the county in D4. Longest unbroken spell: 247 weeks, Feb 13, 2001 to Nov 1, 2005.

Lately

Last drought year: 2025, 27 weeks. 2016-2025: 4 in 10, against 8.1 in 10 for 2000-2015, wetter lately. So far in 2026: 44 of 44 weeks in drought, through Nov 3, 2026.