Why is mold common in Nashville homes?
Moisture. NOAA records show Nashville airport mornings average 84% relative humidity, peaking at 89% in August and September, and the city's creeks flood in heavy rain. EPA says to keep indoor humidity below 60% and dry anything water-damaged within 24 to 48 hours. Patches under about 10 square feet are usually a DIY job.
How humid is Nashville, really?
NOAA's National Centers for Environmental Information keep long-term humidity averages for the Nashville airport station, measured at 6 a.m. and at noon local standard time.[NOAA] Over 1948–2018, the early-morning average was 84% and the midday average 56%.[NOAA]
| Month | 6 a.m. avg. RH | Noon avg. RH |
|---|---|---|
| Jan | 80% | 64% |
| Feb | 80% | 59% |
| Mar | 79% | 54% |
| Apr | 80% | 51% |
| May | 85% | 55% |
| Jun | 86% | 55% |
| Jul | 87% | 56% |
| Aug | 89% | 55% |
| Sep | 89% | 55% |
| Oct | 86% | 53% |
| Nov | 82% | 57% |
| Dec | 81% | 63% |
| Year | 84% | 56% |
Source: NOAA NCEI, Comparative Climatic Data: average relative humidity through 2023 (Nashville, 1948–2018).
Those are outdoor numbers, but they tell you what your A/C, crawl-space vents and basement walls are up against. EPA's target for indoor air is below 60% relative humidity, ideally between 30 and 50%.[EPA] Late summer is the stretch to watch: morning humidity averages 89% in both August and September.[NOAA]
How do floods raise mold risk?
On May 1–2, 2010, 13.57 inches of rain fell at Nashville International Airport, smashing the old two-day record of 6.68 inches; the Cumberland River at Nashville crested at 52.55 feet on May 3.[NWS] Floodwater in walls, floors and ductwork is mold's best friend, which is why EPA's rule matters: dry water-damaged materials within 24 to 48 hours.[EPA] For creek-by-creek detail, see Nashville neighborhoods.
Where does mold hide in Nashville houses?
- Crawl spaces and basements: the lowest, dampest part of the house.
- Around A/C equipment: EPA says to keep drip pans clean and drain lines flowing.[EPA]
- Bathrooms and laundry: vent moisture sources, like dryers, to the outside.[EPA]
- Windows and cold pipes: condensation is a sign the air is too wet.[EPA]
Test, or just fix it?
There are no EPA or federal limits for mold or spores, so a lab number doesn't give you a pass/fail.[EPA] Where sampling does earn its fee is after a cleanup, checking that an area was properly remediated, and it should be done by someone trained to interpret it.[EPA] If you smell mustiness but can't find the source, an inspection that hunts for hidden moisture is usually the better first spend.
DIY or call someone?
EPA's line is about 10 square feet, roughly a 3-by-3-foot patch. Smaller than that, most homeowners can clean it themselves; with a lot of water damage or bigger growth, bring in professional help.[EPA] If you do it yourself, EPA's basics: wear an N-95 respirator, gloves and goggles, scrub hard surfaces with detergent and water, dry everything, and don't paint over mold.[EPA]
On the health side, mold exposure may bring on allergy symptoms or irritation, and in people with asthma it can set off attacks.[EPA][CDC] If someone in the house is sick, talk to a doctor.
Keep reading
Sources
- NOAA NCEI, Comparative Climatic Data: average relative humidity through 2023 (Nashville, 1948–2018)
- NOAA NCEI, Comparative Climatic Data product notes
- EPA, A Brief Guide to Mold, Moisture and Your Home
- National Weather Service Nashville, The May 2010 Flood
- EPA, Mold Testing or Sampling
- CDC, Mold and Your Health
- Angi, mold inspection cost (Oct 2026)
- Angi, mold remediation cost (Jul 2026)