Do not wait for “perfect” season to test. Test when you need the answer. Understand that a winter short-term result may run higher than a breezy July result—and plan follow-ups if numbers are borderline.
Why winter runs higher
Closed windows, furnace operation, and warm indoor air rising increase the pressure difference that pulls soil gas. Frozen or wet soils can also change soil-gas movement.
Why summer can confuse DIY testers
Open-window living (outside of a formal test) lowers typical exposure some days—but a valid short-term test still requires closed-house conditions, which can feel unnatural in July. Follow the protocol anyway.
Real estate reality
You test when the contract allows. Document conditions. If a summer purchase test is mid-3s, discuss risk tolerance and possible retesting after move-in.
Need a local next step? Call (605) 600-6282 to talk through testing, real estate timing, or mitigation for your Rapid City–area home.