Rain has wreaked havoc on the lucrative Friends Life t20 season, with Glamorgan - or their short-form alter-ego the Welsh Dragons - the worst hit of all 18 teams. They lost five of their 10 matches to rain, including three money-spinning home fixtures.
"Cricket is effectively a tourism industry and when it rains, you don't play and the people don't come," he told Press Association Sport. "Cricket has been very badly affected by the rain. I would suggest over a season with this poor weather, you're looking at a six-figure hit."
While that disrupted their attempts to qualify for the quarter-finals, it is the knock-on effect on their end-of-season balance sheet that is perhaps most concerning at a time when every penny counts in the domestic game.
Hamer added: "Over the past six weeks revenues have fallen well below budget because we haven't been able to get games on.
"You don't get ticket sales and, just as importantly, you lose out on secondary spends in the club shops and bars."
Insurance is available for counties to shield themselves against lost income but the cost of such policies is on the rise - and is likely to jump again after the downpours this year.
Counties do not typically insure all matches, instead targeting marquee fixtures and local derbies in a bid to ease the outgoings. Hamer is glad for the safety net, but it can only cushion the blow to a certain extent.
"You can insure, and we have done so, but clearly there is a cost-benefit in terms of premiums," he said. "We insure key matches so our financial loss is minimised but we are a cricket club and it is important that we play cricket. If you don't play, you still incur running costs such as staff.
"The effects going forward can also be substantial: for Twenty20 you can get a lot of casual customers and if their first experience is a bad one, they won't come back. You can't insure against that."