Area Forecast Discussion
Issued by NWS Key West, FL
Issued by NWS Key West, FL
865 FXUS62 KKEY 161500 AFDKEY Area Forecast Discussion National Weather Service Key West FL 1100 AM EDT Sun Aug 16 2026 ...New DISCUSSION, MARINE, AVIATION, PREV DISCUSSION... .KEY MESSAGES... - Temperatures across the Keys will stay warmer than normal this week. Dew points are expected to linger in the upper 70s. - A swath of Saharan dry air will remain across the Keys through the first part of the week. Shower chances are likely to stay significantly below normal until the latter half of the week. - Gentle to moderate easterly breezes at the beginning of the week will slacken to light to gentle over the course of the week, and even become light and variable at times. && .DISCUSSION... Issued at 1040 AM EDT Sun Aug 16 2026 Another calm and toasty day is unfolding along the Florida Keys as high pressure is draped across the area. A widely spread field of fair weather cumulus only points to the tiniest amount of moisture in the lower levels of the vertical column. In fact, our KBYX radar is detecting this field of cloud cover, and radar loops may look like there are some showers out there even though there is no support for some morning activity. It`s simply the radar beam intercepting the clouds. The 12Z KKEY sounding from this morning calculated a PWAT value of 1.51" but layer analysis showed that most of the moisture measured was below approximately 850mb. The average humidity between the surface and 850mb was 90%, from 850mb and higher was an average humidity of 20%. The sounding also showed some saturation around 925mb, but it`s likely that the balloon went through one of the nearby clouds. Satellite derived PWAT values offer another view of the dry air aloft with surface to 850mb PWATs of approximately three quarters of an inch, and just over one quarter of an inch in the layer between 850mb and 700mb. These are just different ways to see just how dry most of our vertical column is even though we are still somewhat moist near the surface. Current observations show dew points along the island chain in the mid to upper 70s with air temperatures in the upper 80s to near 90. Considering that the set up this morning is virtually the same as yesterday, this afternoon will still be on track to be a toasty one. With both air and dew point temperatures expected to climb a few more degrees by peak heating, heat index values could very well occasionally hit the upper 100s, similar to yesterday. The inherited hot and pop-free forecast is unfolding as expected, so no changes are needed with this morning update. Stay cool, neighbors! && .PREV DISCUSSION... Issued at 422 AM EDT Sun Aug 16 2026 Prepare for a prolonged period hot, muggy weather across the Florida Keys this week. There is high confidence that a Saharan Air Layer will set up over Southern Florida early in the work week. Drier air aloft will trap humidity near the surface and result in heat indices approaching 108 degrees. Meanwhile, a mid level trough descending out of Canada into the eastern United States will result in the northward movement of the subtropical ridge. Model ensembles are consistently showing a col region setting up across the Keys during the week, so brace for periods of light and variable winds. Anyone concerned about heat this week should take precautions. While the Saharan Air Layer will not persist through the entire week, it is highly likely that shower coverage will remain below normal for the entire work week. Even after the dust layer is washed out, model ensembles suggest the deeper layers of moisture will continue to be deflected north of the Keys. Statistical guidance suggests rain chances may remain below normal through next weekend. However, the pattern may shift slightly and direct more moisture towards the island chain. && .MARINE... Issued at 1040 AM EDT Sun Aug 16 2026 There are no watches, warnings, or advisories in effect for the Florida Keys local waters. High pressure across the area will encourage light to gentle generally east breezes, occasionally becoming light and variable at times. Rain chances remain very low due to a Saharan Air Layer aloft combined with a mid to upper level dry air mass. && .AVIATION... (15Z TAFS) Issued at 1040 AM EDT Sun Aug 16 2026 VFR conditions with FEW to SCT skies near FL025 will prevail through the TAF period. A Saharan Air Layer may cause occasional VIS observations between 8 and 9 SM, but categorical impacts are not expected. East surface winds will remain near 10 knots initially, but will decrease to 5 to 10 knots by the end of the TAF period. && .PRELIMINARY POINT TEMPS/POPS... Key West 92 83 92 81 / 0 0 0 0 Marathon 90 83 90 81 / 0 0 10 0 && .KEY WATCHES/WARNINGS/ADVISORIES... FL...None. GM...None. && $$ Public/Marine/Fire...DP Aviation/Nowcasts....DP Data Acquisition.....DP Visit us on the web at weather.gov/key Follow us on Facebook and X at: www.facebook.com/nwskeywest www.x.com/nwskeywest