Our tomato plants have stopped producing and the peppers are ready for their last harvest. Most of our flowers are gone except the hardy mums. With the cold overnight temperatures around freezing and cool daytime temperatures, our growing season has come to an end.
Growing Season Dates and Length
The growing season is defined as that part of the year when soil temperatures at 50 cm (20 inches) below the soil surface are higher than biologic zero (5 degrees C, 41 degrees F). As this quantitative determination requires in-ground instrumentation which is not usually available, the growing season can be estimated by approximating the number of frost-free days. The growing season can be approximated as the period of time between the average date of the last killing frost in the spring to the average date of the first killing frost in the fall. This represents a temperature threshold of 28 degrees F or lower at a frequency of 5 years in 10.
The growing season length is determined from daily minimum temperature values. Threshold surface temperatures of 32, 28, and 24 degrees Fahrenheit are generally used to determine the effects of air temperature on plants using the following commonly accepted classification (National Climatic Data Center, 1984b):
- 32 to 29 degrees F is a light freeze: Tender plants are killed, with little destructive effect on other vegetation.
- 28 to 25 degrees F is a moderate freeze: Widely destructive effect on most vegetation with heavy damage to fruit blossoms, tender and semi-hardy plants.
- 24 degrees F and less is a severe freeze: Heavy damage to most plants. At these temperatures, the ground freezes solid, with the depth of the frozen ground dependent on the duration and severity of the freeze, soil moisture, and soil type.
It should be noted that temperatures near the ground may be significantly lower than temperatures measured at five feet, the normal height that air temperatures is observed. It is not unusual for surface temperature and air temperature to vary by four degrees or more. For this reason, the WETS program allows users to select the three threshold temperatures.
Rainfall Totals
Weather History
1899: Muskegon hits 86 degrees for its highest October temperature on record.
1944: Cold air is firmly entrenched in Lower Michigan with record lows of 23 degrees at Grand Rapids and 25 degrees at Muskegon.
On October 15, 1952, Saginaw reported 0.04″ rainfall. This is one of only three days where measurable rain is recorded this October, the driest on record with 0.18″ total. Also for this month, Flint had the 5th driest month on record.
NWS Forecast
Forecast Discussion
- Cooler today with scattered showers near the lake shore Temperatures are starting out in the lower to mid 30s at many locations and a continued feed of cool air from Canada will push against diurnal trend and limit temperature rise to around 50; h8 temps will remain around -4c. High over-lake instability will result in continued lake effect rain showers. North boundary layer flow may result in a few showers clipping the western cwa near the lake shore. Inland, partly cloudy skies are expected. - Continued cool tonight and Wednesday Another frosty night is expected under partly cloudy skies. Temperatures will fall into the lower to mid 30s. The large dome of high pressure to the west responsible for the north winds will slip south to the mid MS Valley and we`ll begin to tap a west wind Tuesday. That will begin the slow warm up that will carry us into the weekend. Dry weather is expected Wednesday. - Cold snap turns warm with fair weather into the weekend Ensembles remain consistent with relatively low spread in solutions for the latter part of this week into early next week. So confidence is higher than normal in a gradual warmup day by day, from Thursday to Monday, with temperatures reaching 10 degrees above normal by Monday. There are also very few if any clouds expected from Thursday through at least Saturday. High pressure will envelop the eastern half of the CONUS later this week, putting Michigan in generally southwesterly flow in the low- levels which will bring in the warmer air. The upper-level ridge will flatten over the weekend, with a weak shortwave trough and attendant surface cold front skirting the northern Great Lakes Sat- Sun. Over the past couple days, the number of ensemble members giving rain to our area for the weekend have dwindled. There are currently just slight chances for showers over West-central to Northwest Lower Michigan Saturday night. After that, the next chance of rain may be Tuesday as the weekend`s cutoff low over the Southwest CONUS gets picked back up into the westerlies, but the ensembles are also somewhat lackluster in the chances for appreciable rain amounts.
My flowers and grass are still growing here. No hard freeze. Sprinklers are on throughout the neighborhood.
I’ll be in Austin TX the next month, will be interesting to see how their fall compares to here. I’m assuming it’ll feel like a “Michigan summer” with 70s and 80s
No frost here last night, but I’ve had 2 frosts so far this season though. Back to back nights at 31.
Looks like most areas did not have a freeze overnight. The low so far here in the Grand Rapids area was mostly in the upper 30’s. The coldest so far this season at Grand Rapids is 36, at Lansing 34. at Muskegon and Holland 37. Last year the 1st low below 32 was on October 23rd
Slim
So technically not the “end” of the growing season for Grand Rapids, but might still be the last freeze warning. No freezing temps the next 2 weeks, and that takes us to November. At some point they will stop issuing freeze warnings when we get late into the season
It will be soon when the NWS will stop issuing frost and freeze warnings. There have been several years recently that the 1st low of 32 or below did not happen until late October and in 2016 it did not happen until November 12th the all time latest is November 14th 1918.
Slim
There was no frost here in MBY as the overnight low so far has been just 38 and that is the current reading with cloudy skies.
Slim
We had frost last week, but none this morning. It was 37 at my home early this morning when I checked.
The official H/L yesterday at Grand Rapids was 54/39 there was a trace of reported rainfall. The sun was out 85% of the time. For today the average H/L is 61/42 the record high of 85 was set in 1947 and 1899. The coldest high of 43 was set in 1944 the warmest low of 64 was set in 1968 the most rainfall of 0.90” fell in 1942. Last year the H/L was 57/41.
Slim