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Warmest sea in United States in April

4,477 coastal locations in United States ranked by their typical April sea temperature. Region-wide average in April: 13.5°C. The top of the list is where to find the warmest swimming this month.

Warmest in April

Howland Island

28.2°C April mean in United States

Regional April average

13.5°C

across all 4,477 coastal locations in United States

Vs annual mean

-2.7°C

below the year-round regional average

What the United States sea feels like in April

Water at this temperature is cold and will feel very cold initially, but the body will get used to it and longer swims are possible. Experienced swimmers can manage several hours of swimming, however hypothermia is still a real risk.

United States monthly average 10.0°C to 22.6°C
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  • Warmest month August 22.6°C
  • Coldest month February 10.0°C
  • Annual mean 16.2°C
  • Months above 20°C 3 of 12

Where April fits in the year

April sits inside the regional pattern shown on the left. Pick a different month to see how the ranking shifts.

All twelve United States month rankings:

United States sea temperature map (live)

The map shows today's latest reading at every United States location. The list below is based on the typical April mean, useful for trip planning weeks or months ahead.

Zoom in to see individual locations. Click a pin for water temperatures. View list →
°C -2 0 1 3 5 7 9 11 13 15 17 19 21 24 27 30 35

Top 50 warmest United States locations in April

Sorted by the typical April mean built from a decade of daily readings at each location. Click any place for its 30-day chart, monthly profile, and full 10-year history.

# Location April mean
1 Howland Island Minor Outlying Islands 28.2°C
2 Palmyra Island Northern Line Islands 28.1°C
3 Jarvis Island Minor Outlying Islands 27.5°C
4 Wake Island, Pacific Ocean Minor Outlying Islands 26.7°C
5 Carysfort Reef, Florida Florida 26.4°C
6 Key Largo Florida 26.3°C
7 Molasses Reef Florida 26.3°C
8 Pennekamp Florida 26.3°C
9 Rodriguez Key Florida 26.3°C
10 Boynton Beach, Lake Worth Florida 26.3°C
11 Lake Worth ICW Florida 26.3°C
12 Lake Worth (ICWW) Florida 26.3°C
13 Lake Worth Pier, Florida 26.3°C
14 Palm Beach, Highway 704 bridge, Lake Worth, Florida Florida 26.3°C
15 Palm Beach, Lake Worth, Florida Florida 26.3°C
16 West Palm Beach Canal, Lake Worth, Florida Florida 26.3°C
17 Alligator Reef Florida 26.3°C
18 Boynton Beach Florida 26.3°C
19 Briny Breezes Florida 26.3°C
20 Card Sound, western side, Florida Florida 26.3°C
21 Channel Two, east, Lower Matecumbe Key, Fla. Bay, Florida Florida 26.3°C
22 Cormorant Point, Key Largo, Card Sound, Florida Florida 26.3°C
23 East Key, southern end, Florida Bay, Florida Florida 26.3°C
24 Garden Cove, Key Largo, Florida Florida 26.3°C
25 Hypoluxo Florida 26.3°C
Show 25 more ▸
26 Indian Key Anchorage, Lower Matecumbe Key, Florida Florida 26.3°C
27 Indian Key, Hawk Channel, Florida Florida 26.3°C
28 Key Largo, South Sound, Key Largo, Florida Florida 26.3°C
29 Lake Worth Florida 26.3°C
30 Lantana Florida 26.3°C
31 Largo Sound, Key Largo, Florida Florida 26.3°C
32 Lignumvitae Key, NE side, Florida Bay, Florida Florida 26.3°C
33 Lignumvitae Key, west side, Florida Bay, Florida Florida 26.3°C
34 Little Basin, Upper Matecumbe Key, Florida Bay, Florida Florida 26.3°C
35 Little Card Point Florida 26.3°C
36 Little Card Sound bridge Florida 26.3°C
37 Main Key, Barnes Sound, Florida Florida 26.3°C
38 Manalapan Florida 26.3°C
39 Manatee Creek, Manatee Bay, Barnes Sound, Florida Florida 26.3°C
40 Mar-a-Lago Florida 26.3°C
41 Matecumbe Bight, Lower Matecumbe Key, Fla. Bay, Florida Florida 26.3°C
42 Matecumbe Harbor, Lower Matecumbe Key, Fla. Bay, Florida Florida 26.3°C
43 Ocean Reef Harbor, Key Largo, Florida Florida 26.3°C
44 Ocean Ridge Florida 26.3°C
45 Plantation Key, Hawk Channel, Florida Florida 26.3°C
46 Point Charles, Key Largo, Florida Florida 26.3°C
47 Pumpkin Key, south end, Card Sound Florida 26.3°C
48 Rock Harbor, Key Largo, Florida Florida 26.3°C
49 Shell Key Channel, Florida Bay, Florida Florida 26.3°C
50 Shell Key, northwest side, Lignumvitae Basin, Florida Florida 26.3°C

Coldest 10 in United States in April

Same data the other way. Helpful if you want to know which United States coasts to avoid for swimming in April.

# Location April mean
1 Point Hope Alaska -1.7°C
2 Barrow Alaska -1.6°C
3 Cape Krusenstern, Kotzebue Sound Alaska -1.6°C
4 Kivalina Alaska -1.6°C
5 Northeast Cape, St. Lawrence Island Alaska -1.6°C
6 Flaxman Island Alaska -1.6°C
7 Fossil River entrance, St. Lawrence Island, Alaska Alaska -1.6°C
8 Outside Lopp Lagoon Alaska -1.6°C
9 Savoonga, St. Lawrence Island Alaska -1.6°C
10 Tin City, Bering Sea Alaska -1.6°C

More on this region