The Gunners are widely reported to be close to a deal for the veteran Czech stopper, who appears set to leave the Barclays Premier League champions and would prefer to keep his family in London.
Cech - who played an instrumental role in Chelsea's success since joining from Rennes in 2004 - may have found himself now as understudy to Thibaut Courtois at Stamford Bridge, but Terry is in no doubt of just what an important player the 33-year-old can be.
In an interview given to talkSPORT from China, where the former England defender is on a promotional tour, Terry said: "I am sure if he does leave the club, which nobody wants to see, but we understand he wants to play football, he is going to be sorely missed
He will improve whatever side he goes to."
Terry added: "There is obviously talk of Arsenal signing Petr and if they do get Pete, that will strengthen them for sure
He will save them 12 to 15 points a season."
Chelsea are expected to improve their own squad again next season.
A season long loan deal with Monaco for Colombia forward Radamel Falcao is expected to be completed after Manchester United opted against making the striker's temporary move permanent at the end of the season.
Terry believes Chelsea cannot afford to stand still if they are to stay ahead of the chasing pack in 2015/2016.
"To be top of the league the whole way through the season was an exceptional thing to do, but you can't kind of dwell on that
We have to start concentrating on next season and try to improve on that again," Terry said.
"When you win the league, you know teams go and spend money to buy the best.
"Manchester City were a little way off this year and will strengthen.
"I feel Arsenal and Manchester United are going to be very strong as well.
"We all know once you win it, everyone wants to beat you the following year, (so) it will be even harder for us to win the league again."
Source : PA
Source: PA