To a small mixing bowl, add and whisk to combine salt, brown sugar, pepper, paprika, onion and garlic powders, dry mustard, celery salt and red pepper flakes. Use a spoon or gloved fingers to break up any clumps, if necessary.
Use to season any type of meat or poultry before grilling, smoking, or roasting in the oven.
Store the bbq dry rub in an airtight container and keep in a cool dry location for up to 6 months.