Fergus Falls
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Fergus Falls clear sky chart from 2005-11-06 to 2024-02-15.

This page is a summary of past forecasts. Even though it's based only on forecasts, some people use these pages as clue to a site's climate. But climate data based on actual observation should be preferred (if you can find it!).

Cloud, Transparency and Seeing forecasts are summarized individually. But because good observing conditions require a combination of minimum cloud cover, transparency and seeing, the individual forecast summaries can be difficult to interpret. The observing conditions section counts the combinations of conditions needed for common types of astronomical observation.

Observing Conditions

The following tables count the occurrence of the combinations of forecast and darkness conditions needed for different observations. Conditions are rated by by what percentage of the hours the observation would likely be attempted are usable.

Observation Type	Minimum conditions for hour to be usable				Out of hours
	Clear of Clouds	Transparency	Seeing	Sky Brightness
Planetary:	50%	(no limit)	Average	(no limit)	Nighttime Hours
Deep Sky:	70%	Average	(no limit)	5.9	Nighttime Hours
CCD Imaging:	70%	Below Average	Poor	(no limit)	Nighttime Hours

Percentages are of nighttime hours per month, or per year, when a particular observing conditions was met. Deep Sky percentages never exceed 50% because the moon is up half the time. Deep sky percentages are much lower for charts at high latitudes because of fewer dark hours in the summer.

Overall

By Month

Individual Forecasts

The length of each colored bar in the "occurrence of each Forecast" column is proportional to the number of times the chart forecast that color. The percentages are of the total number of hours per month, or per year, with a particular forecast. The colors as the same as those used in clear sky charts.

Note: Transparency probabilities are only counted for those hours that have 30% or less cloud cover. Seeing probabilities are only counted for those hours that have 80% or less cloud cover. If that's too tricky, try Observing Conditions instead.

Overall

		Occurrence of each Forecast	Data Points
Cloud Cover	Day	12% 8% 4 8% 6% 4 5% 5% 6% 7% 36%	78037
	Night	11% 9% 4 8% 7% 4 5% 5% 6% 7% 35%	81094
Transparency	Day	46% 8% 14% 22% 9% 1	77730
	Night	47% 8% 14% 21% 10% 1	80922
Seeing	Day	15% 9% 31% 29% 14% 2	14992
	Night	14% 8% 33% 33% 10% 1	25105

By Month

Percentage Cloud Cover SE (2006-)
Color Meanings: Overcast 90% covered 80% covered 70% covered 60% covered 50% covered 40% covered 30% covered 20% covered 10% covered Clear
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	8% 14% 6% 14% 11% 6% 8% 6% 4 5% 18%	2218
	11th to 20th	Day	5% 8% 5% 12% 10% 5% 14% 11% 9% 6% 15%	2411
	21st to end	Day	6% 12% 10% 18% 10% 5% 6% 6% 6% 5% 16%	3020
February	1st to 10th	Day	8% 12% 6% 9% 8% 4 7% 7% 8% 7% 23%	1710
	11th to 20th	Day	7% 11% 4 10% 9% 5% 7% 6% 7% 8% 26%	1610
	21st to end	Day	8% 12% 5% 9% 10% 7% 8% 6% 6% 7% 21%	1412
March	1st to 10th	Day	12% 10% 5% 10% 10% 5% 5% 5% 5% 5% 28%	1908
	11th to 20th	Day	12% 10% 7% 9% 7% 3 5% 5% 6% 7% 32%	1980
	21st to end	Day	14% 12% 5% 10% 8% 4 5% 5% 4 8% 24%	2178
April	1st to 10th	Day	14% 11% 4 8% 6% 3 4 5% 5% 7% 32%	2096
	11th to 20th	Day	17% 10% 4 8% 6% 3 4 4 5% 7% 31%	2312
	21st to end	Day	22% 10% 4 5% 4 3 4 4 4 6% 33%	2340
May	1st to 10th	Day	18% 9% 4 7% 6% 3 4 5% 5% 6% 34%	2340
	11th to 20th	Day	15% 7% 3 5% 6% 3 5% 4 6% 8% 39%	2470
	21st to end	Day	16% 7% 3 5% 5% 3 5% 5% 6% 8% 38%	2787
June	1st to 10th	Day	14% 5% 2 4 5% 3 5% 5% 6% 9% 42%	2700
	11th to 20th	Day	14% 6% 3 5% 4 3 5% 5% 5% 9% 40%	2700
	21st to end	Day	10% 5% 2 5% 4 4 6% 6% 7% 11% 43%	2700
July	1st to 10th	Day	7% 3 1 4 4 3 4 5% 7% 10% 53%	2700
	11th to 20th	Day	9% 3 2 4 4 2 5% 5% 6% 9% 50%	2700
	21st to end	Day	5% 3 2 4 4 3 5% 4 7% 10% 53%	2682
August	1st to 10th	Day	8% 5% 3 5% 4 3 4 6% 7% 10% 46%	2328
	11th to 20th	Day	12% 6% 2 6% 4 4 4 4 7% 8% 44%	2301
	21st to end	Day	9% 3 2 4 4 2 4 4 5% 7% 55%	2574
September	1st to 10th	Day	12% 4 2 4 4 2 4 4 6% 6% 51%	2177
	11th to 20th	Day	12% 5% 2 5% 6% 4 4 5% 5% 6% 47%	1980
	21st to end	Day	15% 5% 2 6% 4 2 4 5% 5% 8% 44%	1980
October	1st to 10th	Day	16% 9% 3 5% 5% 3 5% 5% 5% 6% 39%	1814
	11th to 20th	Day	16% 11% 5% 5% 4 2 4 3 4 5% 41%	1800
	21st to end	Day	18% 11% 4 6% 4 3 4 4 5% 7% 34%	1873
November	1st to 10th	Day	15% 11% 5% 8% 5% 3 5% 4 5% 5% 35%	1570
	11th to 20th	Day	11% 13% 6% 14% 8% 4 5% 4 3 6% 26%	1520
	21st to end	Day	11% 10% 6% 9% 9% 4 5% 5% 5% 7% 30%	1520
December	1st to 10th	Day	7% 13% 6% 13% 10% 5% 8% 5% 5% 6% 23%	1501
	11th to 20th	Day	8% 13% 7% 12% 9% 5% 6% 5% 6% 6% 23%	1683
	21st to end	Day	19% 14% 5% 11% 11% 4 4 3 4 6% 20%	2442
January	1st to 10th	Night	6% 11% 6% 13% 13% 6% 7% 6% 6% 6% 19%	4737
	11th to 20th	Night	6% 9% 6% 12% 11% 8% 13% 9% 6% 6% 14%	4558
	21st to end	Night	6% 13% 11% 13% 8% 4 6% 7% 7% 6% 19%	4644
February	1st to 10th	Night	6% 10% 6% 9% 7% 4 7% 7% 7% 7% 29%	2470
	11th to 20th	Night	6% 10% 5% 9% 7% 3 8% 6% 7% 8% 32%	2332
	21st to end	Night	11% 10% 4 8% 9% 4 6% 6% 5% 6% 30%	1862
March	1st to 10th	Night	11% 9% 4 9% 6% 4 5% 5% 6% 8% 31%	2052
	11th to 20th	Night	11% 10% 4 9% 5% 3 5% 3 5% 7% 38%	1980
	21st to end	Night	15% 9% 4 8% 6% 3 4 4 6% 7% 33%	2178
April	1st to 10th	Night	15% 9% 2 7% 5% 3 4 5% 5% 8% 37%	1861
	11th to 20th	Night	21% 11% 3 6% 5% 3 3 4 4 6% 36%	1599
	21st to end	Night	18% 9% 3 7% 5% 3 4 5% 5% 6% 36%	1620
May	1st to 10th	Night	15% 8% 3 6% 5% 4 4 5% 5% 6% 39%	1620
	11th to 20th	Night	13% 6% 2 5% 5% 3 5% 5% 5% 7% 44%	1422
	21st to end	Night	12% 4 3 4 5% 3 5% 5% 7% 10% 41%	1484
June	1st to 10th	Night	10% 4 2 4 4 2 4 5% 5% 10% 50%	1260
	11th to 20th	Night	9% 4 3 5% 4 3 4 5% 7% 8% 48%	1260
	21st to end	Night	7% 3 2 4 4 3 3 4 6% 11% 51%	1260
July	1st to 10th	Night	4 2 2 3 4 2 4 4 6% 9% 59%	1260
	11th to 20th	Night	5% 3 1 3 3 3 3 5% 5% 8% 63%	1260
	21st to end	Night	4 3 1 3 4 2 5% 5% 6% 7% 60%	1634
August	1st to 10th	Night	7% 4 1 3 4 2 5% 5% 7% 8% 53%	1611
	11th to 20th	Night	9% 5% 2 4 4 2 3 4 5% 7% 56%	1600
	21st to end	Night	8% 3 2 3 4 2 3 3 5% 7% 61%	1782
September	1st to 10th	Night	10% 4 2 4 4 2 3 4 5% 8% 55%	1779
	11th to 20th	Night	9% 5% 2 5% 6% 2 5% 3 5% 6% 53%	1980
	21st to end	Night	12% 5% 2 5% 3 2 3 3 5% 6% 52%	1980
October	1st to 10th	Night	14% 7% 2 6% 5% 3 4 5% 6% 7% 42%	2128
	11th to 20th	Night	15% 9% 3 6% 5% 3 4 4 5% 6% 41%	2160
	21st to end	Night	17% 9% 4 7% 5% 2 4 4 5% 6% 37%	2479
November	1st to 10th	Night	10% 10% 4 7% 6% 3 5% 5% 5% 7% 37%	2508
	11th to 20th	Night	11% 11% 6% 11% 7% 4 5% 4 5% 7% 30%	2660
	21st to end	Night	10% 10% 4 8% 7% 3 5% 5% 6% 8% 35%	2660
December	1st to 10th	Night	9% 11% 6% 10% 9% 5% 6% 6% 7% 6% 25%	2675
	11th to 20th	Night	10% 12% 6% 12% 9% 4 6% 5% 6% 6% 24%	3514
	21st to end	Night	19% 14% 6% 10% 9% 4 5% 5% 4 6% 19%	5225

Transparency (when cloud cover <= 30%)
Color Meanings: Too cloudy to forecast Poor Below Average Average Above average Transparent
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	66% 7% 10% 14% 3	2219
	11th to 20th	Day	62% 8% 12% 15% 3	2411
	21st to end	Day	64% 8% 10% 13% 5%	3020
February	1st to 10th	Day	54% 7% 13% 18% 7%	1710
	11th to 20th	Day	55% 6% 14% 18% 5% 1	1619
	21st to end	Day	58% 8% 11% 15% 7%	1412
March	1st to 10th	Day	57% 7% 14% 16% 6%	1908
	11th to 20th	Day	52% 6% 12% 22% 9%	1980
	21st to end	Day	59% 6% 14% 16% 5%	2178
April	1st to 10th	Day	49% 7% 11% 22% 10% 1	2096
	11th to 20th	Day	52% 7% 12% 17% 11% 1	2312
	21st to end	Day	51% 7% 12% 21% 8% 1	2340
May	1st to 10th	Day	50% 7% 13% 21% 9% 1	2340
	11th to 20th	Day	42% 7% 15% 25% 10% 1	2474
	21st to end	Day	42% 9% 15% 22% 10% 1	2787
June	1st to 10th	Day	37% 9% 16% 28% 10%	2700
	11th to 20th	Day	40% 9% 15% 21% 13% 1	2700
	21st to end	Day	34% 10% 19% 26% 11%	2700
July	1st to 10th	Day	25% 9% 17% 34% 15% 1	2626
	11th to 20th	Day	29% 8% 18% 29% 14% 2	2619
	21st to end	Day	26% 8% 19% 31% 15% 2	2533
August	1st to 10th	Day	32% 9% 18% 28% 10% 3	2314
	11th to 20th	Day	36% 9% 17% 28% 9% 1	2301
	21st to end	Day	29% 7% 14% 33% 16% 2	2574
September	1st to 10th	Day	32% 7% 15% 32% 13% 1	2177
	11th to 20th	Day	36% 7% 17% 29% 10%	1980
	21st to end	Day	37% 7% 15% 30% 9% 1	1980
October	1st to 10th	Day	44% 7% 14% 23% 11%	1814
	11th to 20th	Day	46% 6% 12% 24% 10% 2	1800
	21st to end	Day	51% 6% 14% 22% 7%	1873
November	1st to 10th	Day	51% 6% 12% 20% 10% 1	1570
	11th to 20th	Day	60% 6% 13% 14% 7%	1520
	21st to end	Day	53% 7% 16% 17% 6% 1	1520
December	1st to 10th	Day	60% 8% 13% 15% 4	1501
	11th to 20th	Day	58% 7% 16% 16% 4	1680
	21st to end	Day	67% 5% 9% 15% 4	2442
January	1st to 10th	Night	62% 9% 11% 14% 4	4737
	11th to 20th	Night	65% 10% 10% 9% 5%	4558
	21st to end	Night	60% 9% 11% 15% 4	4644
February	1st to 10th	Night	50% 8% 13% 19% 9% 1	2470
	11th to 20th	Night	49% 7% 12% 21% 10% 1	2333
	21st to end	Night	53% 7% 12% 17% 10% 1	1862
March	1st to 10th	Night	49% 7% 17% 20% 7%	2052
	11th to 20th	Night	46% 5% 13% 24% 11%	1980
	21st to end	Night	49% 7% 15% 20% 6% 1	2178
April	1st to 10th	Night	44% 7% 13% 23% 12% 2	1861
	11th to 20th	Night	50% 5% 8% 23% 12% 2	1599
	21st to end	Night	48% 6% 11% 24% 10% 1	1620
May	1st to 10th	Night	45% 7% 12% 23% 13% 1	1620
	11th to 20th	Night	38% 8% 13% 24% 16% 2	1423
	21st to end	Night	36% 10% 15% 24% 13% 2	1485
June	1st to 10th	Night	30% 7% 18% 32% 12% 1	1260
	11th to 20th	Night	31% 9% 17% 25% 14% 4	1260
	21st to end	Night	25% 9% 20% 30% 14% 2	1260
July	1st to 10th	Night	20% 9% 17% 35% 18% 1	1225
	11th to 20th	Night	20% 8% 15% 35% 18% 5%	1218
	21st to end	Night	21% 8% 16% 34% 17% 3	1544
August	1st to 10th	Night	26% 8% 18% 31% 14% 4	1601
	11th to 20th	Night	27% 8% 18% 31% 14% 1	1600
	21st to end	Night	22% 7% 14% 33% 23% 2	1782
September	1st to 10th	Night	27% 7% 16% 32% 16% 1	1779
	11th to 20th	Night	31% 7% 16% 30% 15%	1980
	21st to end	Night	31% 7% 14% 33% 15%	1980
October	1st to 10th	Night	40% 7% 12% 26% 13% 2	2128
	11th to 20th	Night	43% 5% 12% 25% 13% 1	2160
	21st to end	Night	48% 5% 14% 23% 10%	2479
November	1st to 10th	Night	45% 7% 12% 23% 10% 2	2508
	11th to 20th	Night	53% 7% 14% 16% 9% 1	2660
	21st to end	Night	46% 9% 19% 20% 6% 1	2660
December	1st to 10th	Night	56% 8% 14% 16% 5%	2675
	11th to 20th	Night	57% 9% 14% 14% 4 1	3516
	21st to end	Night	65% 8% 11% 12% 4	5225

Seeing (when cloud cover <= 80%)
Color Meanings: Too cloudy to forecast Bad 1/5 Poor 2/5 Average 3/5 Good 4/5 Excellent 5/5
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	11% 11% 34% 31% 10% 2	270
	11th to 20th	Day	13% 13% 36% 30% 9%	270
	21st to end	Day	11% 11% 38% 21% 16% 2	297
February	1st to 10th	Day	13% 15% 37% 30% 4 1	270
	11th to 20th	Day	17% 13% 39% 23% 8% 1	252
	21st to end	Day	10% 9% 41% 33% 7% 1	198
March	1st to 10th	Day	19% 13% 30% 31% 6% 1	240
	11th to 20th	Day	16% 9% 32% 30% 10% 3	240
	21st to end	Day	20% 9% 33% 22% 13% 3	264
April	1st to 10th	Day	23% 15% 32% 21% 8%	356
	11th to 20th	Day	25% 14% 27% 23% 10% 1	590
	21st to end	Day	22% 11% 33% 20% 12% 2	600
May	1st to 10th	Day	19% 12% 32% 23% 12% 2	603
	11th to 20th	Day	18% 9% 31% 27% 13% 2	625
	21st to end	Day	16% 8% 30% 28% 15% 3	679
June	1st to 10th	Day	11% 7% 28% 30% 21% 3	630
	11th to 20th	Day	14% 8% 38% 26% 13% 2	630
	21st to end	Day	11% 9% 28% 33% 16% 4	630
July	1st to 10th	Day	7% 4 22% 36% 26% 5%	621
	11th to 20th	Day	10% 6% 27% 34% 17% 4	618
	21st to end	Day	6% 3 26% 35% 26% 4	684
August	1st to 10th	Day	8% 3 25% 34% 26% 4	626
	11th to 20th	Day	12% 6% 21% 35% 20% 7%	615
	21st to end	Day	10% 6% 26% 31% 22% 4	693
September	1st to 10th	Day	12% 6% 28% 36% 16% 2	467
	11th to 20th	Day	10% 7% 35% 32% 12% 4	270
	21st to end	Day	20% 14% 31% 23% 10% 1	270
October	1st to 10th	Day	20% 11% 27% 27% 13% 1	270
	11th to 20th	Day	16% 16% 33% 27% 7% 1	270
	21st to end	Day	22% 16% 38% 16% 7% 1	297
November	1st to 10th	Day	24% 10% 26% 31% 9%	270
	11th to 20th	Day	17% 13% 42% 21% 6%	270
	21st to end	Day	17% 13% 37% 27% 5%	270
December	1st to 10th	Day	13% 10% 42% 26% 9% 1	270
	11th to 20th	Day	15% 13% 41% 27% 4	270
	21st to end	Day	23% 10% 38% 22% 6% 1	297
January	1st to 10th	Night	11% 10% 39% 29% 9% 2	950
	11th to 20th	Night	14% 10% 37% 30% 8% 1	950
	21st to end	Night	14% 9% 39% 31% 6% 1	1045
February	1st to 10th	Night	9% 10% 37% 33% 8% 1	950
	11th to 20th	Night	12% 11% 38% 29% 9% 2	902
	21st to end	Night	15% 9% 32% 30% 11% 2	678
March	1st to 10th	Night	14% 9% 38% 30% 9% 1	612
	11th to 20th	Night	15% 10% 37% 31% 6% 1	540
	21st to end	Night	18% 10% 30% 29% 12% 2	594
April	1st to 10th	Night	19% 7% 37% 30% 6% 1	540
	11th to 20th	Night	25% 11% 29% 26% 9% 1	533
	21st to end	Night	22% 8% 32% 26% 12%	540
May	1st to 10th	Night	18% 9% 35% 29% 8%	540
	11th to 20th	Night	15% 8% 34% 32% 10% 1	531
	21st to end	Night	12% 8% 33% 34% 12% 1	584
June	1st to 10th	Night	13% 6% 26% 38% 16% 1	540
	11th to 20th	Night	11% 5% 33% 42% 9%	540
	21st to end	Night	9% 5% 26% 45% 16%	540
July	1st to 10th	Night	4 3 22% 46% 22% 2	525
	11th to 20th	Night	5% 3 27% 48% 16% 1	522
	21st to end	Night	4 3 21% 48% 21% 2	591
August	1st to 10th	Night	8% 3 17% 52% 19% 1	537
	11th to 20th	Night	9% 5% 21% 41% 21% 3	534
	21st to end	Night	8% 3 30% 40% 19% 1	594
September	1st to 10th	Night	12% 4 26% 42% 14% 2	540
	11th to 20th	Night	10% 6% 30% 38% 15% 2	540
	21st to end	Night	14% 6% 36% 31% 11% 1	540
October	1st to 10th	Night	17% 10% 34% 29% 10%	688
	11th to 20th	Night	20% 11% 33% 28% 8% 1	720
	21st to end	Night	21% 11% 34% 28% 6%	895
November	1st to 10th	Night	16% 10% 34% 32% 8%	925
	11th to 20th	Night	16% 13% 35% 28% 7% 1	950
	21st to end	Night	14% 12% 40% 29% 5%	950
December	1st to 10th	Night	14% 10% 37% 31% 8% 1	950
	11th to 20th	Night	17% 10% 37% 30% 6% 1	950
	21st to end	Night	23% 9% 34% 26% 7% 1	1045

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