@sdetweil Thank you for such quick responses…I do appreciate it! Here’s the link: https://api.weather.gov/gridpoints/MFR/104,44/forecast/hourly and here’s a snippet of the return that includes the dates and times that end up (apparently) causing the invalid date error:
"properties": {
    "updated": "2020-06-05T01:18:34+00:00",
    "units": "us",
    "forecastGenerator": "HourlyForecastGenerator",
    "generatedAt": "2020-06-05T04:36:11+00:00",
    "updateTime": "2020-06-05T01:18:34+00:00",
    "validTimes": "2020-06-04T19:00:00+00:00/P7DT17H",
    "elevation": {
        "value": 868.98480000000006,
        "unitCode": "unit:m"
    },
Based on what I can compare against the moment.js documentation, I don’t see anything obvious that would cause the error.