The inspectorate said it was satisfied with some of the improvements in performance in keeping people safe and secure from fires and other risks, "but there are more areas where the service still needs to improve".
However, the fire service had not "addressed future financial challenges and appropriate use of resources" - and equality issues and recruitment and retention were areas of concern.
"The service has a clearly defined set of values but it must make sure they are fully embedded and that all staff understand what is expected and behave appropriately to maintain a professional and effective service to the public, and a working environment where all staff feel safe and supported."
The service revealed it had dealt with 12 times the normal volume of incidents over the course of two days when temperatures across the East topped 40C last week.
"I'm proud of my team. Every single one of us works hard every day to make Essex a safer place for everyone to live, work and travel and we are all committed to improvement.
"You only have to look at how we have responded as a service to the many incidents caused by the recent heatwave, and the support the public has given us, to know we are on the right path."