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Wood Moisture by State: Outdoor EMC for Woodworkers

How wet outdoor wood gets in your area, month by month, and what that means for buying lumber, glue-ups, decks and finishes.

A wooden garden shed with a shingled roof and flower boxes

Wood is never really "dry". It takes on and gives off moisture until it balances with the air around it, at a level called the equilibrium moisture content (EMC). That level depends on humidity and temperature, so it changes with the seasons and from one part of the country to another. When wood moves from one level to another it swells or shrinks across its width, which is why decks open up, tabletops crack and doors stick.

The USDA Forest Products Laboratory has calculated the average monthly EMC of wood kept outdoors (under cover, out of rain and sun) for weather stations across the United States, from at least 30 years of NOAA weather records. We built one page per state from those tables, covering 254 places in all 50 states and Washington, D.C. Each page shows the month-by-month numbers for every city, a short section on each city's climate, the moisture content to aim for, how much a deck board moves and the best months for outdoor builds.

How to use these numbers

All states at a glance

Outdoor EMC of wood in a reference city for each state (driest month, wettest month, year average) and the number of places on each state page
StateCityLowHighAvgPlaces
AlabamaMobile13.0%14.4%13.6%4
AlaskaJuneau13.6%18.1%16.0%11
ArizonaPhoenix4.6%9.5%7.2%5
ArkansasLittle Rock12.8%13.9%13.4%2
CaliforniaLos Angeles12.1%15.1%13.7%16
ColoradoDenver9.4%11.0%10.1%5
ConnecticutHartford10.8%13.3%12.1%2
DelawareWilmington11.5%13.2%12.5%1
FloridaMiami12.3%14.5%13.5%13
GeorgiaAtlanta11.8%14.2%13.0%7
HawaiiHonolulu10.6%13.3%11.6%4
IdahoBoise7.3%15.2%10.8%3
IllinoisChicago12.2%14.9%13.3%6
IndianaIndianapolis12.8%15.7%14.1%4
IowaDes Moines12.4%14.9%13.4%4
KansasWichita11.5%13.9%12.8%5
KentuckyLouisville12.0%14.1%13.3%5
LouisianaNew Orleans14.0%15.3%14.5%5
MainePortland12.1%14.0%13.2%2
MarylandBaltimore11.3%13.1%12.3%1
MassachusettsBoston11.6%13.1%12.2%3
MichiganDetroit12.3%15.1%13.5%9
MinnesotaMinneapolis-St. Paul11.9%14.6%13.2%5
MississippiJackson13.7%15.1%14.3%3
MissouriSt. Louis12.4%14.9%13.5%4
MontanaMissoula9.8%17.6%13.1%8
NebraskaOmaha12.1%14.8%13.4%7
NevadaLas Vegas4.0%8.5%6.2%5
New HampshireConcord11.4%13.9%12.8%2
New JerseyNewark10.6%12.6%11.8%2
New MexicoAlbuquerque6.4%10.7%8.5%3
New YorkNew York11.0%12.6%12.0%7
North CarolinaRaleigh11.7%14.5%13.1%6
North DakotaFargo11.9%15.2%13.8%3
OhioCleveland12.6%14.6%13.5%8
OklahomaOklahoma City11.7%13.4%12.6%2
OregonPortland11.7%17.4%14.2%7
PennsylvaniaPhiladelphia11.2%13.0%12.2%7
Rhode IslandProvidence11.1%13.0%12.2%1
South CarolinaCharleston12.4%14.6%13.4%3
South DakotaSioux Falls12.6%15.3%13.6%4
TennesseeMemphis12.2%13.8%12.9%5
TexasDallas-Ft. Worth11.6%13.9%12.9%17
UtahSalt Lake City7.1%14.9%10.6%3
VermontBurlington11.7%14.2%13.0%1
VirginiaRichmond11.3%13.8%12.8%5
WashingtonSeattle-Tacoma12.2%16.5%14.3%5
Washington, D.C.Washington11.1%12.6%11.9%1
West VirginiaCharleston11.4%14.3%13.2%5
WisconsinMadison12.5%15.7%14.1%4
WyomingCheyenne9.7%10.8%10.3%4

Every city in the data

Find the station nearest you, or the one with the most similar climate. Each link goes straight to that city on its state page.

What isn't covered

The source tables list specific weather stations, not every town, so use the nearest city with a similar climate (a coastal city tells you little about the mountains two hours inland). U.S. territories (Puerto Rico and the Pacific islands in the source table) are not included on this site. The values are long-term averages from records before 1997 and describe wood under cover; a rain-soaked board or a board in an air-conditioned room will read differently, so a moisture meter is still the final word.

New to the subject? Start with why a 2x4 isn't 2 by 4: shrinkage from drying is part of the answer.

Sources