Yes, a rainstorm can elevate the radon levels in a home temporarily, which is why radon testing for a real estate transaction is not recommended during a storm or if one is expected during the test period. There are two ways that heavy rain can raise radon levels:

1) A storm reduces the barometric pressure in the air and, because barometric pressure is simply the weight of the air in the atmosphere pressing down on the earth, lower pressure allows more radon gas to rise from the soil and a flow into a home. 

2) Heavy rain for a long period saturates the surface soil surrounding a home, blocking the flow of radon up into the outside air, but not under the home. So, with the normal pathways out of the soil for radon near the house blocked, the flow coming up under the home increases.

    But a ordinary afternoon rain shower, like the kind we get on summer days here in Central Florida, is not a reason to postpone  a radon test.

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Here’s links to a collection of our blog posts about “RADON":

• Is a radon mitigation fan required to be on a dedicated circuit breaker/fuse in the electric panel?

• What happens to a radon test result if the windows were opened, the test device moved, or there was any other evidence of tampering during the test? 

• Where do I find the Florida laws regarding radon?

• Can I test vacant land for radon before building a house? 

• Is radon mitigation possible for a condominium?

• Do radon mitigation systems require maintenance?

• What is the average life expectancy of a radon mitigation system?  

• Do older houses have higher radon levels than new houses? 

• Can the seller tamper with a homebuyer's radon test to change the results?

• How long does it take to get the results of a radon test? 

• Will opening the windows reduce the radon level in a house?

• How was it determined that between 15,000 and 22,000 lung cancer deaths each year are caused by radon?

• Can a homebuyer do their own radon test for a real estate transaction with a self-test kit?

• What is the danger of radon in well water?

• What are the symptoms of radon poisoning? 

• Does Florida have radon?

• Where does radon come from? 

• For how many years does an old radon test result remain valid?

• Should homeowners get a pre-listing radon test before selling their home?

• What are a homebuyer's options when the radon test comes back high (4.0 pico-curies/liter or more)? 

• Do granite countertops emit radon?

• How can I tell if a house has a radon mitigation system? 

• Can a mobile/manufactured home have a high radon problem?

• Do I need to test for radon when buying a condominium? 

• What does a radon mitigation contractor do to lower the radon level in a home?

• How can not testing for radon be an expensive mistake for homebuyers? 

• Will the radon test come back sky-high in a house that has been empty and closed-up for months? 

• What is radon? Should I be concerned about it?

• Should I buy a house with a high radon level? 

• What is the average radon level of indoor and outdoor air in America?

• What is the operating cost of a radon mitigation system? 

• Should I buy a house with a radon mitigation system?

• Does the buyer or seller of a home pay for radon mitigation when the radon test comes back high? 

• What is the probability of having high radon in a Florida house?

• How quickly do I need to reduce a high radon level in my house? 

• Does a home inspector check for radon?

• What are the problems with underground return air ducts? 

• What is the probability of having high radon in a Florida house?

• What factors can change radon test levels up or down? 

• How do I know if a radon mitigation system is working? 

• Can I sell a house with a high radon level?

• Does heavy rain change radon levels? 

• Does barometric pressure change radon levels?

• Do high winds affect radon levels? 

• What radon level is dangerous?

    Visit our RADON page for other related blog posts on this subject, or go to the INDEX for a complete listing of all our articles.