Almunia has found himself behind both new number one Wojciech Szczesny and Lukasz Fabianski in the pecking order at the Emirates in recent times and is hoping that a successful spell at Upton Park may lead to better opportunities.
"It's been a hard time for me recently. I was not playing at Arsenal and was frustrated," he said.
"I was hoping to leave and try to play for another team and have minutes on the field. The most important thing is playing football and feeling the ball.
"[West Ham] are the strongest team in the Championship. I hope I can help them be top of the league come the end of the season."
The Spaniard played his first game on Saturday in West Ham's 2-2 draw at Crystal Palace.