Ffos Las' fixture on Friday is subject to a 7.30am inspection on raceday morning as officials at the Welsh venue must assess conditions in case the track is waterlogged.
Clerk of the course Tim Long said on Thursday morning: "We had a large amount of rain on Tuesday - 28 millimetres - but we are raceable.
"It's heavy ground, but there are forecasts which suggest we could have a large amount of rain today - certainly 15mm plus. We will be fine with the bottom end of that, but we just feel it's correct to make people aware of what's going on."
Exeter's meeting on Sunday is subject to an 8am inspection on Saturday morning as, although the track was found to have been raceable on Thursday morning, more rain has been forecast.
Exeter general manager Tim Darby said: "We had eight millimetres of rain overnight on top of nearly 80mm in the last three days, but we are raceable at the moment.
"There is more rain forecast so we'll have an inspection on Saturday and see where we are. The course here dries very quickly and we have a strong wind at the moment, which will help."
The meeting at Towcester on Sunday is subject to a precautionary 8.30am inspection on Friday and while the going is described as good to soft, soft in places, there are areas of standing water.
Clerk of the course Robert Bellamy said: "We've been dry today but we had 19 millimetres of rain yesterday and have standing water in places.
"The forecast for tonight and tomorrow is pretty horrendous and it doesn't look good at this stage, but we'll reassess things in the morning and see where we are."