Report

Space weather: K index 4, active. Data from NOAA. Maximum usable frequency 12 megahertz, measured by the Idaho Falls ionosonde via KC2G: long-distance paths open through 30 meters, 20 meters and up closed. Critical frequency 4.1 megahertz, so 80 meters is good for NVIS.

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, 32 percent lit. The Orionid meteor shower peaks Wednesday, October 21, a meteor scatter opportunity on 6 and 2 meters. Moonbounce: the moon peaks tomorrow at 9:02 AM, 71 degrees high and 3 percent closer than average, a good time to listen for EME signals on 2 meters and up.

160 and 80 meters often peak right at sunrise on paths to the west, just before the D layer forms and absorbs them.

Amateur satellite passes for the next four hours. No passes above 30 degrees in the next four hours. Frequencies and live status at amsat.org/status. Pass predictions at n2yo.com.

Satellite tip: passes above 30 degrees are the easiest. Low passes mean longer paths and more obstructions.

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 17 hours ago: Newer data is not yet available, and conditions may have changed. over Oakland, a duct at 250 to 330 meters, good for 33 centimeters and up. No matching ducts along the coast or toward Hawaii, so the enhancement is likely local. K6EEG's experimental tropo forecast, based on NOAA atmospheric model data, for the next 12 hours. Bay Area coast, peaking around 5 AM: ducting expected on 70 centimeters, 90 percent; a chance of ducting on 2 meters, 50 percent. Southern California coast, peaking around 11 PM: ducting expected on 70 centimeters, 95 percent; ducting likely on 2 meters, 65 percent. Pacific Northwest coast, peaking around 11 PM: ducting likely on 70 centimeters, 75 percent; a slight chance of ducting on 2 meters, 25 percent. Nothing toward Hawaii.

Tropo openings favor horizontal antennas. For CW, try 144.05 to 144.1 megahertz on 2 meters, and 432.1 on 70 centimeters.

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.

Many handhelds can receive NOAA Weather Radio. Program the local channels.

Current weather conditions at San Francisco International Airport: All values in SI units. Clear. Temperature 23 degrees Celsius. Dew point 12 degrees Celsius. Relative humidity 50 percent. Wind calm. Barometric pressure 1013 hectopascals, normal. Visibility 16 kilometers.

Know how long your backup power lasts. Test it under real load, not just with a meter.

National Weather Service forecast. Values converted to SI units. Tonight: Mostly clear, with a low around 16 degrees Celsius. West southwest wind 0.0 to 4.0 meters per second. Monday: Sunny. High near 27 degrees Celsius, with temperatures falling to around 24 degrees Celsius in the afternoon. West northwest wind 0.0 to 4.5 meters per second. Monday Night: Mostly clear, with a low around 16 degrees Celsius. West southwest wind 0.9 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 0.9 meters, slight seas, dominant period 15 seconds, from the south southwest. That's long-period ground swell. Wind at the buoy 4 meters per second from the northwest. Ocean water temperature 16 degrees Celsius. San Francisco Bay water temperature 20 degrees Celsius. Golden Gate currents: maximum ebb 1.6 meters per second at 11:14 PM, then slack water at 4:09 AM, then maximum flood 1.1 meters per second at 6:50 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 6 micrograms per cubic meter, rated good. Ozone is 46 parts per billion. Nitrogen dioxide is 7 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 2.5, near Pinnacles. 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.