Web alarm clock for 12:22 p.m.
While you watch the clock for the right moment to cover the gathered coconuts before rain reaches them, set the alarm for 12:22 pm. It keeps you from moving too early while the harvest is still being sorted, yet leaves 38 minutes before 1:00 pm for pulling tarpaulins across the pile and securing their edges.
Rain on a metal roof, farm equipment, or conversation nearby can easily drown out a browser alarm. Raise your phone or computer volume, choose an audible signal, and keep the speaker close enough to hear while you stay near the coconuts. Test the sound before relying on it. If the browser page is closed or the device falls asleep, the alarm may not sound, leaving the coconuts uncovered when the shower arrives.
After the coconuts are protected at midday, avoid turning the remaining afternoon into one long stretch of work if you still need sleep later. Finish tying the cover, put wet ropes and tools where they can dry, and note any section that needs checking after the rain. Keeping the later tasks contained helps preserve a clear stopping point, so the work around 12:22 pm does not quietly take over the hours you meant to leave for rest.