Report

Space weather: solar flux 105, 10 below its 90-day average of 115. Maximum usable frequency 10 megahertz, measured by the Idaho Falls ionosonde via KC2G: long-distance paths open through 40 meters, 30 meters marginal, 20 meters and up closed. Critical frequency 3.4 megahertz, too low for NVIS right now. K index 4, minor geomagnetic storm. 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, 40 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.

Rooftop solar inverters shut down at sunset, often lowering the HF noise floor for the evening. They come back on at sunrise.

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, and at 6:24 AM rising in the north northwest, 41 degrees. FO 29, linear transponder, on a schedule: at 7:03 AM rising in the south southeast, 88 degrees, overhead. PO 101, FM, on a schedule: at 7:15 AM rising in the south southeast, 45 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: on 70 centimeter downlinks, Doppler shift is about plus or minus 10 kilohertz. Start high at rise and tune down through the pass.

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 11 hours ago: No ducting strong enough for amateur VHF or UHF bands over Oakland.

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.

Check into a local net this week. Regular net practice is what makes emergency nets work.

Current weather conditions at San Francisco International Airport: All values in SI units. Clear. Temperature 18 degrees Celsius. Dew point 13 degrees Celsius. Relative humidity 73 percent. Wind calm. Barometric pressure 1011 hectopascals, normal. Visibility 16 kilometers.

National Weather Service forecast. Values converted to SI units. Overnight: Partly cloudy, with a low around 17 degrees Celsius. West southwest wind 0.0 to 1.3 meters per second. Sunday: Partly sunny. High near 29 degrees Celsius, with temperatures falling to around 25 degrees Celsius in the afternoon. West northwest wind 0.4 to 5.4 meters per second. Sunday Night: Mostly clear, with a low around 16 degrees Celsius. West wind 0.0 to 4.0 meters per second.

Tide predictions for today at the San Francisco Embarcadero gauge. Low tide at 12:34 AM, minus 0.02 meters. High tide at 8:16 AM, 1.42 meters. Low tide at 12:48 PM, 1.00 meters. High tide at 6:32 PM, 1.72 meters.

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 1.2 meters, slight seas, dominant period 8 seconds, from the west northwest. Wind at the buoy 3 meters per second from the northwest. Ocean water temperature 16 degrees Celsius. San Francisco Bay water temperature 19 degrees Celsius. Golden Gate currents: maximum flood 1.0 meters per second at 5:40 AM, then slack water at 9:03 AM, then maximum ebb 0.8 meters per second at 11:39 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.

Sign up for your county's emergency alerts, such as Alert SF in San Francisco. Hams are often among the first to relay that information.

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.

Text, don't call. Text messages often get through when voice calls can't, and they keep lines open for emergency calls.