Best efficiency
Mini-splitENERGY STAR
MRCOOL DIY 4th Gen 12K
Cooling
12,000 BTU
Covers
500 ft²
Efficiency
22 SEER2
Noise
32 dB
$1099 est.
typical retail price Hot & Dry · ~11¢/kWh · 4-month season
Air conditioning in Idaho: sizing, costs & the right units
Idaho's populated southwest — Boise, Nampa, the Treasure Valley — is high-desert hot and dry: summers routinely hit the 90s and low 100s with low humidity and big day-to-night swings, while the northern panhandle and mountains stay cooler. Boise is one of the fastest-growing metros in the country, and AC is standard in the valley.
Updated June 2026
What to look for in Idaho
Dry-climate cooling is forgiving on humidity but demanding on sun and peak temperature — let sun exposure drive sizing and check a unit's maximum operating temperature for the hottest afternoons. Evaporative ('swamp') coolers work in Idaho's dry shoulder months; for the July peak, refrigerant AC is the reliable choice. Cheap hydropower keeps bills low.
What cooling costs in Idaho
Estimated at Idaho's average residential rate (~11¢/kWh, approximate) and 8 hours/day. "Per season" assumes 4 cooling months. Your utility rate and usage will vary.
| Unit | Efficiency | Est. / month | Est. / season |
|---|---|---|---|
| Senville LETO SENL-12CD Mini-split | 21.2 SEER2 | $17 | $68 |
| LG Dual Inverter LW1022IVSM Window | 15 CEER | $18 | $72 |
| BLACK+DECKER BPACT14WT Portable | 6.1 CEER | $61 | $244 |
Climate-matched
All 49 units Units that fit Idaho's climate
WindowENERGY STAR
LG LW1521ERSM 15,000 BTU
Cooling
15,000 BTU
Covers
800 ft²
Efficiency
11.8 CEER
Noise
53 dB
$549 est.
typical retail price
Editor's pick
WindowENERGY STAR
LG Dual Inverter LW1022IVSM
Cooling
10,000 BTU
Covers
450 ft²
Efficiency
15 CEER
Noise
44 dB
$429 est.
typical retail priceIdaho AC questions, answered
How many BTU do I need in Idaho?
Use the Hot & Dry zone — about 8% above baseline for the heat, without a humidity penalty. A 300 ft² Boise room lands near 6,500–7,000 BTU, but a west-facing room in full afternoon sun should size up.
Does a swamp cooler work in Idaho?
Yes, in the dry early and late summer — evaporative cooling is cheap and effective in Idaho's low humidity. During the hottest, occasionally smoky weeks of July and August, refrigerant AC is the more reliable choice.
What does AC cost to run in Idaho?
At ~11¢/kWh — among the lowest rates in the country thanks to hydropower — an efficient 12,000 BTU unit runs about $18–26/month over Boise's hot, dry summer.
Electricity rates are approximate state averages; check your utility bill for your exact rate.