Best Day to Spearfish Calculator
There is no single best day to spearfish. The best day is the one where wave height, wind, swell period and water clarity all land inside a safe, huntable band at the same time. This free calculator turns those five readings into one honest verdict. Set what your forecast shows and it returns a score from 0 to 100 plus a plain go, caution or no-go call. It follows the same rule the live spearo forecast uses: any single dangerous factor caps the result, because the sea only has to be unsafe in one way to keep you out. A flat swell over muddy water is still a wasted trip. Use it to plan the week, then read the sea again on site before you get in.
Rate today's sea state
Conditions line up. This is a day worth getting in the water.
What is holding it back
- The wind is crossing or onto the coast, not off it.
- The water is only so-so, so visibility may be short.
- Wave83
- Wind80
- Direction62
- Period100
- Water62
A guide, not a green light. Read the sea on site, know your exit, and never dive a marginal day alone.
How the calculator works
- Set the wave height. Drag the wave slider to the significant wave height your forecast shows, in metres.
- Set the wind. Set the wind speed in knots and pick whether it blows onto, across or off the coast.
- Set the swell period. Choose the peak swell period in seconds; a clean mid range scores best.
- Set the water clarity. Pick how the water reads: muddy, okay or clear.
- Read the verdict. The widget scores the day from 0 to 100 and returns a go, caution or no-go call with the reasons.
Check a real forecast
See the live seven-day verdict for a spot near you:
FAQ
What is the best day to spearfish?
The best day is when the wave stays low, the wind is light and preferably offshore, the swell period sits in a clean mid range and the water reads clear. When all four line up you get long visibility and a safe entry and exit. This tool scores exactly that overlap.
How is the score calculated?
Each of the five inputs gets its own sub-score, then they are blended by weight into a 0 to 100 figure. Wave height and water clarity carry the most weight. If any factor is dangerous the verdict is capped at no-go, no matter how good the rest look.
Does a calm sea always mean good spearfishing?
No. Flat water with poor visibility is a wasted trip, and a small wave on a long-period groundswell can still throw heavy sets that seal a rock exit. The calculator weighs clarity and period alongside wave height so a deceptively calm day does not read green.
Can I use this instead of checking on site?
No. It is a planning guide built on the numbers you enter, not a live reading of your beach. Always look at the real sea, find your exit and never dive a marginal day alone.
This calculator is a planning aid, not a safety clearance. Conditions change fast at the water. Read the sea on site, know your exit and dive within your training.