The average junior engineer salary at Napa was $145,506 , which is 37 percent higher than the average salary for this job in California, and 26 percent higher than the national average for this job . Junior Engineer salaries at Napa typically range from $141,630 to $149,382 (25th to 75th percentile). The highest reported junior engineer salary was $149,382. There are 2 employees at Napa with the job title junior engineer.