Historical weather data, all-time temperature records, and monthly climate averages for Riverhead, NY. Explore typical weather conditions by week for trip planning, and see how today compares to the historical record.
April 4th in Riverhead typically lands in that awkward shoulder season — expect a high around 54° and a low near 38°, with nearly a coin-flip chance of rain. The date has swung wildly over 87 years of records, from a balmy 72° in 2010 down to a bitter 22° back in 1954, so don't put the layers away just yet.
Riverhead's weather has real range — the thermometer has climbed as high as 100° on July 21, 1991, and crashed to -8° on January 18, 1982, a 108-degree spread that shows this isn't a place of meteorological moderation. The wettest single day on record dumped 6.87 inches in August 1946, and a remarkable 24 inches of snow fell in a single day as recently as February 23, 2026.
Summer is the clear sweet spot here, with highs peaking around 84–85° during the week of July 16–22, while mid-January bottoms out at a raw 38° average high. If you're rain-averse, avoid mid-March, which is the wettest stretch of the year averaging over an inch of precipitation for the week.