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 Cool North · ~12¢/kWh · 3-month season
Air conditioning in Montana: sizing, costs & the right units
Montana is mostly cool and dry, but the eastern plains (Billings, Glendive) and lower valleys see hot, dry summer stretches into the 90s and 100s, while the western mountains stay cool. It's a low-AC state with big day-to-night temperature swings that often let homes coast on night air — until a heat wave settles in.
Updated June 2026
What to look for in Montana
Dry air and cool nights mean many Montana homes only need cooling for the hottest afternoons — an efficient unit or a heat-pump mini-split for the main room is plenty, and the mini-split adds welcome heat in the long winter. In the hot, dry east an evaporative cooler is a cheap option for the driest weeks; cheap power keeps any unit affordable to run.
What cooling costs in Montana
Estimated at Montana's average residential rate (~12¢/kWh, approximate) and 8 hours/day. "Per season" assumes 3 cooling months. Your utility rate and usage will vary.
| Unit | Efficiency | Est. / month | Est. / season |
|---|---|---|---|
| Senville LETO SENL-12CD Mini-split | 21.2 SEER2 | $19 | $57 |
| LG Dual Inverter LW1022IVSM Window | 15 CEER | $19 | $57 |
| BLACK+DECKER BPACT14WT Portable | 6.1 CEER | $66 | $198 |
Climate-matched
All 49 units Units that fit Montana's climate
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 price
WindowENERGY STAR
Keystone KSTAW12CE
Cooling
12,000 BTU
Covers
550 ft²
Efficiency
12 CEER
Noise
58 dB
$360 est.
typical retail priceMontana AC questions, answered
How many BTU do I need in Montana?
Use the Cool North zone and lean on cool nights — a 300 ft² room near 6,000–7,000 BTU handles most afternoons, though hot eastern-Montana rooms in full sun should size up.
Do I really need AC in Montana?
Often only for the hottest weeks. Dry air and cool nights let many homes coast, but eastern Montana's 95°F+ stretches make a unit worthwhile, and a heat-pump mini-split also covers the long heating season efficiently.
What does AC cost to run in Montana?
At ~12¢/kWh — among the cheapest in the country — an efficient 12,000 BTU unit runs about $18–26/month, and the short season keeps annual spend low.
Electricity rates are approximate state averages; check your utility bill for your exact rate.