Monthly Kachemak Bay report, January 2026

Authors

Affiliations

Martin Renner

CSS, under contract to NOAA/NCCOS Kasitsna Bay Lab

Kris Holderied

NOAA/NCCOS Kasitsna Bay Lab

Paul Cziko

NOAA/NCCOS Kasitsna Bay Lab

Summary

January 2026 was cold in Kachemak Bay. Air temperatures were the lowest recorded this century. Water temperatures were the lowest temperatures we ever recorded in January, bested only by February 2012. Sea surface temperatures in the Gulf of Alaska were also colder than normal, however, most of the rest of the North Pacific remained in a positive temperature anomaly. Salinity values in Kachemak Bay were near normal after being fresher than normal for most of 2025.

Conditions

The month leading up to this survey was unusually cold. Average air temperatures at Homer airport in late December to early January were about 7 °C below the long-term mean and over 2 °C below the 10th percentile for that month (Figure 1). The low on 8 January 2026 (-24.4 °C) was the lowest air temperature recorded since the turn of the century. Hans, Kris, and Paul conducted the KBL monthly survey on 20 January, covering the AlongBay and T9 transects in sea states varying between Beaufort 1 and Beaufort 2.

A complete set of up-to-date graphs can be found on the Google Drive: section plots and time sections.

Figure 1: Recent temperature and precipitation at Homer Airport, compared to their seasonal means.

Physical oceanography

Temperature

Water temperatures during this survey ranged from a minimum of 0.6 °C at station 9-10 (2 m depth), in the inner bay, to a maximum of 4.2 °C at AlongBay-4 (15 m depth) in the outer bay. As expected for this month, the inner bay was colder than the outer bay, with the main transition near the Homer Spit (as indicated by the densely spaced contour lines in Figure 2 (a), top-left panel).

T9 is situated around km 30 of the AlongBay transect, cross-sectioning this transition zone. Sloping salinity and temperature contour lines showed that there was an influx of warmer, more saline water at depth, especially on the south side, and an outflow of colder, fresher water on the surface at the north side of T9 (Figure 2 (b)).

(a) AlongBay Transect from Kachemak Bay entrance (left) to Bear Cove (right).

(b) T9 Transect, across bay from Homer Spit (left) to China Poot Bay (right).

Figure 2: Longitudinal and cross-sections of main parameters from the current cruise (left column) and their respective anomaly, i.e. the difference between the current measurements and the long-term monthly mean (2012-current) at the respective place and depth.

On a larger scale, satellite data showed a similar trend for sea surface temperatures, as observed here for Kachemak Bay, for Cook Inlet: warm waters from the Gulf of Alaska, gradually cooled, as they moved into the increasingly shallow waters of the upper inlet (Figure 3).

Figure 3: Sea surface temperature in the Gulf of Alaska, based on satellite remote sensing

Everywhere in the bay, and at all depths, water temperatures were below the long-term mean, in some parts reaching over 2 standard deviations or 3 °C below normal (top-right of Figure 2), making this the coldest January for water temperatures in Kachemak Bay since the beginning of our records (we do not have measurements for January 2012; only February 2012 was even colder). Satellite measurements indicated that sea surface temperatures in the Gulf of Alaska were also colder than normal. Globally, the Gulf of Alaska stood out as one of the few areas currently colder than normal. Almost everywhere, the North Pacific remained substantially warmer than normal (global SST anomaly). For three years (2022-2024) temperatures in Kachemak Bay stayed remarkably close to normal, were about 1 SD above normal for most of 2025, but swung over to the negative side in January 2026 (Figure 4, Figure 5).

Figure 4: Water temperature at the Homer Harbor SWMP station, operated by the KBNERR, at approximately 7 m depth (This is the deeper of two sensors, but is still located in the surface layer).

Figure 5: Bottom-water temperature at mid-bay CTD station T9-6 compared to the seasonal long-term mean.

Figure 6: Bottom water temperature at the outer Kachemak Bay (station AlongBay-5).

Figure 7: Long-term temperature and salinity profiles at mid-bay (T9-6).

Salinity

Salinity values ranged from 28.1 PSU at 9-9 (1m depth) in the outer bay to 31.6 at 9-6 (92m depth) in the outer bay. Inner bay waters were fresher than outer bay waters. The outer bay was more saline than the inner bay, but in contrast to many other years, much of the water column was still stratified. Signs of a fully mixed water column were evident in the western outer bay (Figure 2 (a)). Similarly to the heat wave years of 2014-16, the bay experienced anomalously warm waters for the first 2/3 of 2025. Since this fall, salinity swung to being saltier than normal, but was close to normal in January 2026 (Figure 8).

Figure 8: Variability of deep-water salinity at T9-6 compared to the seasonal long-term mean.

Turbidity

No major spatial differences in turbidity levels were noted, nor were turbidity levels consistently away from expected values (Figure 2).

Biological conditions

Phytoplankton

Chlorophyll concentrations were close to zero throughout Kachemak Bay, showing no areas of concentrated activity, as may be expected during January, and especially with temperatures this cold (Figure 2).

Figure 9: Trends and seasonal anomaly of Chlorophyll concentrations at T9-6 (mean from surface to 85 m depth)

Mailing list

Please email Martin at martin.renner@noaa.gov if you would like to be added to or removed from this mailing list.