Report

Space weather: solar flux 105, 10 below its 90-day average of 115. Maximum usable frequency 9 megahertz, measured by the Idaho Falls ionosonde via KC2G: long-distance paths open through 40 meters, 30 meters and up closed. Critical frequency 2.9 megahertz, too low for NVIS right now. K index 3, active. No significant flares. Data from NOAA.

We're in the declining phase of Solar Cycle 25, which peaked in October 2024. Sunspots and solar flux are trending down toward the next minimum, expected around 2030.

Sun and moon, Pacific Daylight Time: sunrise 7:08 AM, sunset 6:48 PM, day length 11 hours 40 minutes. Moonrise 12:27 AM at 58 degrees, east northeast; moonset 3:40 PM at 299 degrees, west northwest. Waning crescent, 41 percent lit. The Orionid meteor shower peaks Wednesday, October 21, a meteor scatter opportunity on 6 and 2 meters. Moonbounce: the moon peaks today at 8:07 AM, 76 degrees high and 3 percent closer than average, a good time to listen for EME signals on 2 meters and up.

After sunrise the D layer builds, and 160 and 80 meters go quiet on daytime paths within an hour or two.

Amateur satellite passes for the next four hours. RS 44, linear transponder, SSB and CW: at 4:31 AM rising in the north, 39 degrees. For the next pass, RS 44: inverting linear transponder, uplink near 435.64 megahertz lower sideband, downlink near 145.965 upper sideband. Frequencies and live status at amsat.org/status. Pass predictions at n2yo.com.

Satellite tip: AMSAT's live status page shows which satellites are working. Check before a pass, and log your own reports to help others.

DX activity, via the cluster network and hamqsl.com. None spotted by West Coast stations right now. No aurora or 6 meter E-skip.

Tropospheric ducting, from balloon soundings 9 hours ago: No ducting strong enough for amateur VHF or UHF bands over Oakland. K6EEG's experimental tropo forecast, based on NOAA atmospheric model data, for the next 12 hours. Bay Area coast, peaking around 10 AM: ducting expected on 70 centimeters, 80 percent; a chance of ducting on 2 meters, 35 percent. Southern California coast: ducting likely on 70 centimeters, 65 percent; a slight chance of ducting on 2 meters, 20 percent. Nothing toward Hawaii.

Events. The California QSO Party, now under way, California stations in demand. IARU Region 1UHF/Microwaves Contest, today. VHF-UHF FT8 Activity Contest, on Wednesday.

Club and community announcements. The SF Amateur Radio Club meets on the third Friday of each month, 7 PM at the Randall Museum. Visit sfarc.org for more details.

Test your go-kit monthly, and rotate batteries and supplies. Keep your FCC license information current in the ULS, including your email address. The FCC sends license notices by email.

Current weather conditions at San Francisco International Airport: Clear. Temperature 66 degrees Fahrenheit. Dew point 55 degrees Fahrenheit. Relative humidity 68 percent. Wind calm. Barometric pressure 29.85 inches of mercury, normal. Visibility 10 miles.

Batteries and radios in parked cars degrade in heat. Keep go-kit batteries somewhere cool.

National Weather Service forecast. Overnight: Partly cloudy, with a low around 62. West southwest wind 0 to 3 miles per hour. Sunday: Partly sunny. High near 85, with temperatures falling to around 77 in the afternoon. West northwest wind 1 to 12 miles per hour. Sunday Night: Mostly clear, with a low around 61. West wind 0 to 9 miles per hour.

Tide predictions for today at the San Francisco Embarcadero gauge. Low tide at 12:34 AM, minus 0.1 feet. High tide at 8:16 AM, 4.7 feet. Low tide at 12:48 PM, 3.3 feet. High tide at 6:32 PM, 5.6 feet.

Ocean and bay conditions. No marine advisories in effect. From the San Francisco buoy, 18 nautical miles west of the Golden Gate: significant wave height 4 feet, slight seas, dominant period 8 seconds, from the west northwest. Wind at the buoy 10 knots from the northwest. Ocean water temperature 60 degrees Fahrenheit. San Francisco Bay water temperature 68 degrees Fahrenheit. Golden Gate currents: slack water at 3:01 AM, then maximum flood 1.9 knots at 5:40 AM, then slack water at 9:03 AM.

Air quality for field operations, from the Bay Area Air District's San Francisco Arkansas Street monitoring station. Fine particulate matter, PM2.5, is 10 micrograms per cubic meter, rated good. Ozone is 19 parts per billion. Nitrogen dioxide is 16 parts per billion. For more information visit the Bay Area Air District or openaq.org on the web.

Seismic awareness for emergency communicators: no Bay Area earthquakes of magnitude 2.5 or greater in the past 24 hours. Largest in California in the past 24 hours: magnitude 2.4, near Alum Rock. No earthquakes of magnitude 6 or greater worldwide. Seismic data from earthquake.usgs.gov.

A significant local earthquake is the Bay Area's most likely trigger for ARES and RACES activation. Keep go-kits and backup power ready.