What exempts a Catholic from going to Mass on Sunday at church?

What constitutes a valid reason for not attending the Eucharistic celebration at your local church on Sundays?

First of all what does Canon Law say on this matter?

On Sundays and other holy days of obligation, the faithful are obliged to assist at Mass. They are also to abstain from such work or business that would inhibit the worship to be given to God, the joy proper to the Lord’s Day, or the due relaxation of mind and body - (canon 1247).

The Catechism of the Catholic Church reiterates this precept of the Church, but gives more insights.

The Sunday Eucharist is the foundation and confirmation of all Christian practice. For this reason the faithful are obliged to participate in the Eucharist on days of obligation, unless excused for a serious reason (for example, illness, the care of infants) or dispensed by their own pastor. Those who deliberately fail in this obligation commit a grave sin. - (CCC 2181)

Confusion sets in though at what constitutes “serious reason.” For the purpose of this blog post, we are only considering “serious reason” as it pertains to illness. If you are in doubt regarding other serious reasons for missing Mass on a Sunday or holy day, I strongly urge you to talk to your pastor.

What constitutes “serious reason” to miss Mass?

The first thing to keep in mind is that you cannot judge your own circumstances by anyone else’s. For example, two people I know who battled cancer handled differently the same situation of whether or not to attend church during their illness.

The first person did not miss a single Mass obligation from the day he entered the Catholic Church as a young man until the day he died, a few days after attending a Sunday Mass for the very last time. All who knew him were edified by his determination to keep going to Sunday Mass until the very end. The second person was warned by her doctor that chemotherapy would wipe out her immune system, making her extremely susceptible to deadly complications, and chose not to attend church until her course of treatment was completed.

Which person was right? They both were. Both of these people carefully assessed their circumstances and capabilities, and both made the choice they felt in conscience was the correct one for them. Neither one would have dreamed of binding anyone else’s conscience by the same choice they made for themselves.

Most of us though do not face life-or-death consequences when we are trying to decide whether or not to go to Mass. We usually have lesser concerns to consider. Here are a few of them:

Am I contagious? Every year during cold and flu season, parish bulletins issue standard pleas to congregants to avoid the sign of peace and receiving the precious blood from the chalice when ill. But when you know you have an illness that is easily spread to other people, why would you go to a large gathering of people in the first place—especially when there may be people in that gathering who are not sick now, but whose health is fragile and who can easily fall seriously ill from someone else’s minor cold? Perhaps more pastors should be using the bulletin to tell people who are contagious to stay home.

Do I look ill? If you have red, watering eyes, a runny nose, or a recurring sneeze, people around you are going to assume you are contagious, whether you are or not. Even if what you have is a sinus infection or an allergic reaction, your appearance likely is going to worry all of the congregants who are seated near you. How well will they be able to concentrate on the Mass when they hear you blowing your nose or see you wiping your streaming eyes?

Can I sit through Mass? Without getting specific, there are certain medical conditions that may not be contagious, but that may require you to either walk around or visit the restroom frequently. Unless you know for certain you can sit near an exit or a restroom, your constant movement may cause distraction for others and should be considered when deciding whether to go to Mass.

Can I travel safely? Are you driving yourself, or riding with someone else? If you are driving yourself, are you taking medication that could cause you to become sleepy? Could your symptoms inhibit your driving ability? For example, constantly streaming eyes or a hacking cough that causes you to close your eyes may make you an unsafe driver. - When to Stay Home from Mass

Thus it would be safe to assume that for the elderly to drive in extremely bad weather, it would be advisable to get a ride with someone more competent in driving in such conditions or ask for an exemption from the normal Sunday obligation. I am sure your scenario described above constitutes a valid reason for staying home, unless alternative means can be found.