The average junior engineer salary at Napa was $151,662 , which is 30 percent higher than the average salary for this job in California, and 30 percent higher than the national average for this job . Junior Engineer salaries at Napa typically range from $149,335 to $153,988 (25th to 75th percentile). The highest reported junior engineer salary was $153,988. There are 2 employees at Napa with the job title junior engineer.