Maunakea Weather Center

Maunakea Observatories Forecast
5 PM HST Friday 13 February (0300 UTC Saturday 14 February) 2026
Warning(s)
High humidity
Chance for fog/ice
Cloud Cover and Fog/Precipitation Forecast
There is a small risk for fog/ice as humidity lingers near 50-70% for the night; precipitation is unlikely. Broken to overcast clouds are set to build in overhead, blanketing skies as the night progresses.

Summary of Key Meteorological Variables
Summit temperatures will be near -1 C, with light southerly winds and seeing near 0.6-0.7 arcseconds for the night. Precipitable water is expected to exceed 4 mm through the night.
Discussion
While the tradewind inversion will remain intact near 8 thousand feet probably through most of Saturday night, there is a small/moderate chance for fog/ice as humidity lingers near 50-70% during that time. A brief influx of mid-level moisture may subtly raise the odds on fog/ice around sunrise Sunday and for that evening, but this risk will subside (along with humidity) as the air mass dries out/stabilize through that night. A more well-defined inversion will eventually take shape near 7-8 thousand feet, and combined with the departure of the moisture/instability, will allow humidity to settle back in around 10-20% and ensure dry/stable conditions for Monday and Tuesday night. Some afternoon clouds are possible for tomorrow, then could turn extensive for Sunday, only to taper for early next week.

More mid/upper-level clouds are set to rapidly build in from the NW and south through the day, contributing to overcast skies over much of the weekend. Skies will open up again as these clouds shift eastward for Monday night, leaving clear skies for Tuesday night.

Precipitable water is expected to linger near or exceed 4 mm probably through most of Monday night, but will likely drop toward 1 mm through Tuesday night.

Despite mostly light/laminar flow at and above the summit, a fairly wet air mass, combined with weak instability will contribute to slightly poorer than average seeing through Saturday night. There is a possibility that a modest influx of moisture will subtly degrade seeing mainly for Sunday evening, but seeing should improve as the air mass begins to dry out as the night progresses. A drier air mass is set to build in through Monday night, but there is a chance that free atmospheric turbulence will limit seeing from improving during that time. Seeing will likely settle back in near 0.4-0.5 arcseconds as this turbulence subsides and dry/stable conditions prevail for Tuesday night.

Little change since the morning forecast....Widespread deep moisture/clouds will linger over and especially to the west of the Big Island as a weak trough persists to the west of the state, before deepening again over the weekend. While the surface ridge will still remain quasi-stationary/steady to the NE, the mid-level ridge will remain rather indistinct, which will not help to disperse/detrain the lingering moisture in the area. Still, subsidence from the ridge will help reform an inversion near 8 thousand feet that should remain intact into the weekend. There is still a small/moderate risk for fog/ice as humidity hovers around 50-70% during that time. Precipitation is unlikely, mainly due to the lack of low-level forcing as well as clouds near summit-level. However, widespread high clouds are set to quickly build into the area as the aforementioned trough digs into the tropics over the next 12-24 hours. These clouds are set to thicken and blanket summit skies over much of the weekend. There is a chance that this trough will introduce fresh instability into the area and eventually reorganize the surrounding moisture into a frontal band, which may shift over the Big Island mainly around the daytime on Sunday. This may briefly erode the inversion, saturate much of the air mass and increase the risk for fog, ice and short-lived flurries during that time. This band will is expected to quickly shift southward and away from the Big Island as a new mid-level ridge broadens to the NE early Monday morning. This could help open up skies and dry/stabilize the air mass, significantly improving conditions (as well as PW/Seeing) for the early part of next week.
5 Day Forecast Summary (Graphical Trend)
HST Cloud Fog/Precip Temp Wind Seeing PW
Cover (%) Height (km) Probability (%) (Celsius) (Dir/MPH) (Arcseconds) (mm)
Fri Feb 13 - 8 PM60-807.5-1025 / 5-1SSE/0-100.5-0.84-6
Sat Feb 14 - 2 AM80-1006-1020 / 5-1S/0-100.5-0.84-6
2 PM80-1006-1040 / 103.5ENE/0-10NaN4-8
8 PM80-1006-1030 / 5-0.5ESE/0-100.5-0.84-8
Sun Feb 15 - 2 AM80-1006-1035 / 5-0.5S/0-100.55-0.854-8
2 PM80-1004-1075 / 253N/5-15NaN6-10
8 PM70-906-1040 / 10-0.5NNE/5-150.55-0.954-8
Mon Feb 16 - 2 AM60-806-920 / 5-0.5N/5-150.5-0.84-6
2 PM20-406-810 / 04.5NNW/10-20NaN4-6
Tue Feb 17 - 2 AM10-306-80 / 00NNE/5-150.45-0.753-5
2 PM0-20Clear0 / 05.5NE/5-15NaN2-4
Wed Feb 18 - 2 AM0-20Clear0 / 01ESE/5-150.3-0.61-2
2 PM0-20Clear0 / 06SE/5-15NaN1-2
Rise and Set times for the Sun and Moon
Night (HST) Sun Set Twilight End Twilight Beg Sun Rise Moon Rise Moon Set Illumination (%) RA DEC
Fri Feb 13 - Sat Feb 14 18:30 19:35 5:37 6:42 4:51 N/A 10 19 28.5 -25 56
Sat Feb 14 - Sun Feb 15 18:30 19:35 5:37 6:42 5:35 N/A 5 20 20.9 -22 47
Sun Feb 15 - Mon Feb 16 18:31 19:36 5:36 6:41 6:17 17:13 1 21 11.5 -18 31
Mon Feb 16 - Tue Feb 17 18:31 19:36 5:36 6:40 6:55 18:10 0 22 00.6 -13 20
Tue Feb 17 - Wed Feb 18 18:31 19:36 5:35 6:40 7:31 19:05 1 22 48.4 -7 29
Forecast Issued by: Ryan Lyman
Next update at 10 AM HST (2000 UTC) Monday 16 February 2026.
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