Whitefish
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Whitefish clear sky chart from 2005-11-06 to 2026-07-31.

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	16% 10% 3 8% 5% 4 4 3 5% 6% 36%	138212
	Night	15% 11% 4 9% 5% 4 4 3 5% 6% 33%	134941
Transparency	Day	33% 35% 7% 16% 8% 1	141712
	Night	35% 34% 7% 15% 8% 1	139531
Seeing	Day	23% 14% 32% 21% 8% 2	17603
	Night	22% 11% 29% 27% 10% 1	26739

By Month

Percentage Cloud Cover NE (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	14% 18% 7% 11% 4 3 4 2 4 5% 27%	4094
	11th to 20th	Day	11% 17% 7% 17% 7% 5% 5% 3 4 4 19%	4593
	21st to end	Day	9% 17% 7% 15% 7% 5% 4 4 4 5% 23%	5471
February	1st to 10th	Day	11% 18% 5% 11% 6% 6% 4 4 4 6% 26%	1890
	11th to 20th	Day	13% 15% 5% 11% 6% 4 4 4 4 5% 28%	1843
	21st to end	Day	12% 17% 6% 13% 6% 5% 5% 3 4 5% 25%	1690
March	1st to 10th	Day	18% 13% 3 8% 4 4 4 3 4 5% 33%	4803
	11th to 20th	Day	14% 13% 5% 10% 5% 4 5% 3 5% 7% 28%	5090
	21st to end	Day	16% 14% 6% 8% 4 4 3 3 4 5% 34%	5586
April	1st to 10th	Day	17% 14% 4 7% 4 4 4 4 5% 6% 30%	2473
	11th to 20th	Day	20% 11% 3 6% 4 3 4 3 5% 6% 36%	2702
	21st to end	Day	22% 9% 2 6% 4 3 3 3 5% 6% 36%	2730
May	1st to 10th	Day	16% 8% 2 7% 4 4 4 3 5% 7% 39%	7642
	11th to 20th	Day	17% 8% 2 6% 4 4 4 3 5% 7% 41%	8043
	21st to end	Day	18% 7% 2 5% 4 4 4 3 4 6% 44%	9409
June	1st to 10th	Day	15% 7% 2 7% 5% 4 4 4 5% 8% 39%	3150
	11th to 20th	Day	14% 7% 2 6% 5% 4 4 4 6% 8% 40%	3150
	21st to end	Day	17% 6% 2 6% 6% 4 5% 4 6% 7% 37%	3150
July	1st to 10th	Day	16% 7% 2 6% 4 5% 5% 3 6% 9% 37%	6969
	11th to 20th	Day	11% 4 2 5% 4 5% 4 4 5% 7% 49%	6956
	21st to end	Day	10% 5% 2 5% 4 3 4 4 5% 8% 49%	6847
August	1st to 10th	Day	11% 6% 2 6% 5% 5% 5% 4 6% 9% 41%	4234
	11th to 20th	Day	17% 6% 2 5% 4 4 4 4 6% 8% 42%	4174
	21st to end	Day	13% 5% 2 6% 4 4 5% 3 5% 8% 47%	4675
September	1st to 10th	Day	13% 7% 3 7% 5% 4 5% 4 5% 8% 39%	2383
	11th to 20th	Day	13% 5% 1 4 4 5% 4 4 5% 8% 47%	2200
	21st to end	Day	20% 7% 3 7% 4 3 4 3 4 6% 39%	2200
October	1st to 10th	Day	19% 7% 2 6% 4 4 4 3 5% 7% 39%	2045
	11th to 20th	Day	25% 8% 2 7% 6% 5% 5% 4 5% 6% 27%	2000
	21st to end	Day	26% 12% 3 8% 3 4 4 3 5% 6% 26%	2050
November	1st to 10th	Day	19% 13% 2 8% 5% 5% 4 3 6% 7% 30%	1785
	11th to 20th	Day	16% 16% 5% 9% 5% 5% 4 3 5% 6% 26%	1680
	21st to end	Day	21% 20% 4 9% 5% 5% 4 3 4 5% 20%	1680
December	1st to 10th	Day	13% 21% 6% 9% 5% 5% 5% 4 6% 6% 20%	2581
	11th to 20th	Day	18% 17% 7% 12% 5% 3 3 3 4 4 23%	2691
	21st to end	Day	28% 19% 6% 9% 4 3 3 2 3 4 18%	3553
January	1st to 10th	Night	11% 14% 7% 13% 6% 4 5% 4 5% 6% 24%	8831
	11th to 20th	Night	12% 18% 6% 13% 5% 4 5% 4 5% 5% 23%	8319
	21st to end	Night	9% 16% 7% 14% 6% 6% 5% 4 6% 6% 22%	8723
February	1st to 10th	Night	12% 15% 5% 12% 5% 5% 5% 4 5% 5% 27%	2730
	11th to 20th	Night	11% 15% 4 11% 7% 5% 4 4 6% 6% 27%	2663
	21st to end	Night	12% 17% 5% 9% 6% 5% 5% 4 4 6% 26%	2113
March	1st to 10th	Night	17% 10% 4 8% 5% 4 4 3 5% 6% 36%	5256
	11th to 20th	Night	13% 10% 4 10% 5% 5% 5% 4 5% 7% 31%	5089
	21st to end	Night	18% 10% 6% 9% 4 4 3 2 4 5% 33%	5588
April	1st to 10th	Night	19% 10% 3 7% 4 5% 4 4 5% 6% 33%	2163
	11th to 20th	Night	19% 9% 3 6% 4 3 4 3 5% 6% 39%	1867
	21st to end	Night	20% 9% 2 9% 5% 5% 4 3 4 5% 34%	1890
May	1st to 10th	Night	15% 7% 2 8% 5% 5% 4 3 5% 8% 38%	5257
	11th to 20th	Night	15% 7% 3 5% 4 4 4 3 5% 6% 42%	4801
	21st to end	Night	15% 8% 3 6% 4 3 4 3 4 6% 45%	4780
June	1st to 10th	Night	13% 6% 3 7% 4 5% 5% 5% 7% 8% 39%	1470
	11th to 20th	Night	11% 6% 2 6% 4 5% 5% 4 6% 8% 43%	1470
	21st to end	Night	13% 6% 2 7% 4 5% 4 4 6% 8% 41%	1470
July	1st to 10th	Night	14% 7% 2 5% 4 4 3 3 6% 8% 43%	3230
	11th to 20th	Night	11% 4 1 5% 4 3 4 3 5% 7% 52%	3230
	21st to end	Night	10% 4 2 5% 4 4 4 3 5% 8% 52%	4219
August	1st to 10th	Night	10% 6% 2 6% 3 5% 5% 4 6% 8% 44%	2915
	11th to 20th	Night	14% 5% 2 6% 4 3 4 3 5% 8% 46%	2875
	21st to end	Night	11% 4 2 5% 3 3 4 3 4 7% 52%	3223
September	1st to 10th	Night	13% 6% 2 6% 4 4 4 3 5% 7% 45%	1994
	11th to 20th	Night	13% 4 1 4 3 3 4 3 5% 8% 53%	2200
	21st to end	Night	17% 8% 3 7% 4 4 3 3 5% 7% 41%	2200
October	1st to 10th	Night	20% 7% 2 6% 3 4 3 3 5% 7% 40%	2355
	11th to 20th	Night	24% 9% 3 7% 5% 4 4 3 4 6% 31%	2400
	21st to end	Night	25% 10% 3 8% 4 5% 4 3 5% 5% 29%	2788
November	1st to 10th	Night	18% 11% 3 6% 4 4 4 4 5% 7% 33%	2731
	11th to 20th	Night	18% 14% 4 9% 5% 5% 5% 3 5% 7% 27%	2940
	21st to end	Night	20% 17% 5% 8% 5% 4 4 3 5% 5% 23%	2940
December	1st to 10th	Night	15% 19% 4 9% 5% 5% 6% 4 5% 5% 23%	4818
	11th to 20th	Night	17% 15% 5% 12% 5% 4 4 3 4 5% 25%	5736
	21st to end	Night	25% 21% 6% 10% 4 3 3 2 4 4 18%	7667

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	50% 21% 6% 16% 6% 2	4095
	11th to 20th	Day	58% 20% 6% 8% 6% 1	4624
	21st to end	Day	51% 22% 5% 12% 10%	5471
February	1st to 10th	Day	25% 59% 4 9% 3	1890
	11th to 20th	Day	25% 58% 4 8% 5%	1852
	21st to end	Day	25% 59% 2 8% 4	1690
March	1st to 10th	Day	42% 28% 7% 7% 13% 3	4806
	11th to 20th	Day	44% 28% 9% 11% 8% 1	5090
	21st to end	Day	42% 28% 9% 11% 9% 2	5586
April	1st to 10th	Day	23% 58% 4 9% 6%	2473
	11th to 20th	Day	22% 59% 3 10% 6% 1	2702
	21st to end	Day	21% 59% 5% 10% 5% 1	2730
May	1st to 10th	Day	35% 23% 7% 22% 11% 2	7651
	11th to 20th	Day	36% 23% 7% 19% 13% 2	8047
	21st to end	Day	35% 22% 6% 19% 13% 3	9410
June	1st to 10th	Day	17% 59% 3 11% 8% 2	3150
	11th to 20th	Day	18% 59% 4 11% 7% 1	3150
	21st to end	Day	20% 58% 4 10% 7% 1	3150
July	1st to 10th	Day	35% 27% 11% 19% 7% 1	6896
	11th to 20th	Day	25% 26% 9% 32% 6%	6875
	21st to end	Day	23% 26% 9% 27% 14%	6655
August	1st to 10th	Day	23% 39% 7% 22% 8% 1	4221
	11th to 20th	Day	27% 38% 10% 17% 8%	4213
	21st to end	Day	23% 37% 10% 22% 8%	4674
September	1st to 10th	Day	20% 58% 7% 11% 5%	2383
	11th to 20th	Day	12% 57% 6% 17% 8%	2200
	21st to end	Day	19% 56% 8% 12% 5% 1	2200
October	1st to 10th	Day	23% 35% 6% 22% 14%	3331
	11th to 20th	Day	26% 37% 10% 23% 6%	3240
	21st to end	Day	38% 36% 8% 12% 6%	3287
November	1st to 10th	Day	30% 52% 5% 10% 3	1785
	11th to 20th	Day	29% 55% 6% 7% 3	1680
	21st to end	Day	30% 54% 5% 7% 4	1680
December	1st to 10th	Day	42% 37% 12% 7% 2	2581
	11th to 20th	Day	48% 30% 4 9% 8% 1	2691
	21st to end	Day	56% 26% 2 10% 6%	3553
January	1st to 10th	Night	49% 21% 7% 15% 7% 1	8831
	11th to 20th	Night	52% 20% 9% 11% 8%	8363
	21st to end	Night	50% 23% 6% 11% 8% 1	8723
February	1st to 10th	Night	24% 59% 3 9% 5%	2730
	11th to 20th	Night	24% 57% 4 10% 5%	2665
	21st to end	Night	25% 59% 2 8% 5%	2113
March	1st to 10th	Night	38% 28% 7% 12% 11% 4	5266
	11th to 20th	Night	40% 28% 11% 14% 6% 1	5090
	21st to end	Night	43% 26% 3 13% 12% 2	5588
April	1st to 10th	Night	24% 59% 3 9% 6%	2163
	11th to 20th	Night	20% 59% 3 9% 8% 1	1867
	21st to end	Night	23% 58% 4 9% 6% 1	1890
May	1st to 10th	Night	36% 23% 5% 22% 12% 2	5264
	11th to 20th	Night	35% 22% 6% 22% 13% 2	4802
	21st to end	Night	36% 22% 4 24% 12% 3	4781
June	1st to 10th	Night	16% 59% 3 12% 7% 3	1470
	11th to 20th	Night	17% 59% 5% 11% 8% 1	1470
	21st to end	Night	16% 58% 5% 13% 7% 1	1470
July	1st to 10th	Night	32% 27% 9% 21% 9% 1	3195
	11th to 20th	Night	24% 26% 9% 33% 8%	3188
	21st to end	Night	23% 26% 9% 28% 14%	4099
August	1st to 10th	Night	24% 36% 9% 21% 9%	2904
	11th to 20th	Night	26% 37% 14% 17% 7%	2902
	21st to end	Night	20% 37% 8% 25% 9%	3223
September	1st to 10th	Night	17% 57% 7% 13% 5%	1994
	11th to 20th	Night	12% 57% 6% 18% 7%	2200
	21st to end	Night	18% 57% 7% 11% 7%	2200
October	1st to 10th	Night	23% 35% 7% 22% 12%	3849
	11th to 20th	Night	24% 36% 9% 24% 6%	3899
	21st to end	Night	31% 37% 14% 13% 5%	4501
November	1st to 10th	Night	27% 53% 6% 9% 5%	2731
	11th to 20th	Night	27% 54% 7% 9% 4	2940
	21st to end	Night	30% 54% 4 7% 4	2940
December	1st to 10th	Night	42% 36% 9% 9% 3	4818
	11th to 20th	Night	44% 31% 5% 8% 11% 1	5735
	21st to end	Night	55% 25% 5% 10% 6%	7667

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	23% 14% 35% 21% 7%	220
	11th to 20th	Day	23% 18% 35% 19% 5% 1	314
	21st to end	Day	25% 12% 33% 23% 7% 1	363
February	1st to 10th	Day	27% 21% 35% 12% 5%	330
	11th to 20th	Day	25% 21% 39% 12% 3	330
	21st to end	Day	30% 25% 34% 10% 1	273
March	1st to 10th	Day	28% 21% 31% 16% 4	426
	11th to 20th	Day	27% 15% 34% 18% 6% 1	540
	21st to end	Day	30% 16% 30% 19% 4 1	594
April	1st to 10th	Day	28% 16% 28% 20% 8% 1	540
	11th to 20th	Day	32% 17% 23% 17% 9% 2	532
	21st to end	Day	32% 16% 29% 14% 7% 2	540
May	1st to 10th	Day	22% 15% 34% 20% 6% 3	543
	11th to 20th	Day	23% 17% 28% 21% 8% 3	567
	21st to end	Day	20% 13% 34% 24% 7% 2	732
June	1st to 10th	Day	18% 16% 38% 21% 6% 1	780
	11th to 20th	Day	19% 15% 36% 21% 7% 1	780
	21st to end	Day	23% 15% 33% 21% 7% 2	780
July	1st to 10th	Day	13% 16% 35% 26% 9% 2	771
	11th to 20th	Day	13% 14% 35% 27% 8% 4	768
	21st to end	Day	12% 8% 40% 26% 9% 4	753
August	1st to 10th	Day	17% 7% 28% 29% 15% 5%	526
	11th to 20th	Day	16% 6% 28% 28% 14% 8%	519
	21st to end	Day	16% 10% 30% 23% 14% 6%	583
September	1st to 10th	Day	16% 11% 28% 27% 12% 6%	530
	11th to 20th	Day	16% 6% 25% 31% 15% 7%	530
	21st to end	Day	25% 12% 23% 25% 12% 4	530
October	1st to 10th	Day	25% 12% 29% 22% 11% 2	530
	11th to 20th	Day	31% 12% 34% 17% 5% 1	530
	21st to end	Day	33% 16% 32% 16% 2 1	433
November	1st to 10th	Day	33% 15% 33% 13% 4 1	294
	11th to 20th	Day	25% 19% 35% 18% 4	220
	21st to end	Day	32% 21% 27% 15% 5%	220
December	1st to 10th	Day	27% 13% 33% 20% 6% 1	220
	11th to 20th	Day	32% 18% 35% 13% 2	220
	21st to end	Day	38% 17% 27% 13% 4 1	242
January	1st to 10th	Night	22% 13% 32% 26% 7% 1	1050
	11th to 20th	Night	26% 15% 25% 26% 7% 1	1050
	21st to end	Night	21% 10% 31% 28% 9% 1	1039
February	1st to 10th	Night	19% 16% 34% 26% 5%	840
	11th to 20th	Night	21% 14% 33% 25% 6% 1	823
	21st to end	Night	23% 16% 33% 23% 5%	692
March	1st to 10th	Night	18% 16% 36% 24% 5%	840
	11th to 20th	Night	21% 13% 35% 24% 7% 1	840
	21st to end	Night	23% 13% 32% 25% 6% 1	924
April	1st to 10th	Night	25% 14% 31% 25% 6% 1	782
	11th to 20th	Night	26% 12% 26% 25% 10% 1	623
	21st to end	Night	24% 11% 27% 27% 11%	630
May	1st to 10th	Night	16% 8% 31% 33% 10% 1	630
	11th to 20th	Night	16% 9% 29% 34% 11%	474
	21st to end	Night	15% 9% 31% 32% 13%	455
June	1st to 10th	Night	17% 8% 34% 33% 9%	420
	11th to 20th	Night	15% 7% 30% 38% 10%	420
	21st to end	Night	17% 5% 29% 35% 13% 1	420
July	1st to 10th	Night	10% 6% 29% 42% 12% 1	410
	11th to 20th	Night	10% 4 27% 44% 14%	408
	21st to end	Night	12% 5% 26% 37% 19% 1	684
August	1st to 10th	Night	13% 3 22% 41% 20% 1	597
	11th to 20th	Night	14% 2 21% 37% 23% 3	594
	21st to end	Night	16% 5% 23% 32% 22% 2	660
September	1st to 10th	Night	16% 8% 25% 31% 17% 3	750
	11th to 20th	Night	15% 8% 24% 30% 20% 4	800
	21st to end	Night	20% 7% 24% 29% 18% 2	800
October	1st to 10th	Night	23% 8% 26% 31% 11% 2	800
	11th to 20th	Night	30% 11% 28% 23% 8% 1	800
	21st to end	Night	30% 12% 27% 24% 5% 1	880
November	1st to 10th	Night	27% 12% 29% 25% 7%	820
	11th to 20th	Night	28% 14% 26% 23% 8%	840
	21st to end	Night	32% 14% 29% 20% 5%	840
December	1st to 10th	Night	27% 14% 31% 21% 7%	899
	11th to 20th	Night	27% 15% 31% 20% 6% 1	1050
	21st to end	Night	34% 13% 26% 20% 7%	1155

Page generated at 2026-07-28 03:25:20. Version ac07

Copyright © 2026 Attilla Danko.