Historical weather data, all-time temperature records, and monthly climate averages for Sussex, WI. Explore typical weather conditions by week for trip planning, and see how today compares to the historical record.
April 4th in Sussex lands right in that shoulder-season sweet spot — historically speaking, expect a cool 49° high and a frosty 30° low, with a 40% shot at rain. The date has seen it all, from a balmy 73° back in 1956 to a brutal 13° in 1995, so don't put the layers away just yet.
Sussex doesn't mess around at the extremes — this is a place that has baked at 104° in July 2012 and frozen to -40° in January 1982, a swing of 144 degrees. The wettest single day on record dropped a remarkable 8.62 inches in August 2025, and a February 2008 snowstorm buried the area under 15.3 inches in one shot.
Summer is the clear headliner, with highs peaking around 81-82° during the third week of July and June bringing the most rain at about an inch per week. Winter is no joke — January highs average just 27°, making mid-January through February the stretch to avoid if you're cold-averse. Spring and fall offer a pleasant but unpredictable middle ground, with April and October averaging highs in the mid-50s to low 60s.