Lake City
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Lake City clear sky chart from 2005-11-06 to 2025-11-18.

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	9% 5% 2 6% 5% 5% 5% 5% 7% 9% 41%	126748
	Night	10% 6% 2 6% 4 4 5% 4 6% 9% 44%	123615
Transparency	Day	37% 6% 15% 19% 16% 7%	130498
	Night	37% 5% 14% 19% 16% 8%	127934
Seeing	Day	11% 5% 18% 25% 24% 17%	16703
	Night	12% 4 19% 35% 26% 5%	26708

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	10% 6% 2 5% 3 2 4 3 4 6% 56%	4056
	11th to 20th	Day	19% 8% 3 6% 4 5% 3 2 4 7% 39%	4060
	21st to end	Day	10% 5% 2 6% 4 4 5% 3 6% 9% 48%	4678
February	1st to 10th	Day	15% 7% 3 5% 4 3 4 3 5% 7% 44%	2000
	11th to 20th	Day	13% 6% 2 6% 3 4 4 4 5% 5% 47%	1948
	21st to end	Day	13% 7% 2 5% 4 3 3 4 5% 6% 48%	1652
March	1st to 10th	Day	16% 7% 3 6% 4 4 4 4 6% 8% 40%	4935
	11th to 20th	Day	8% 4 1 4 3 4 4 4 6% 7% 54%	4980
	21st to end	Day	12% 4 2 4 4 3 4 4 5% 8% 49%	5465
April	1st to 10th	Day	8% 5% 2 6% 4 4 4 5% 6% 8% 48%	2200
	11th to 20th	Day	9% 5% 2 6% 5% 4 4 4 6% 7% 47%	2176
	21st to end	Day	5% 4 1 4 4 5% 5% 4 7% 7% 54%	2550
May	1st to 10th	Day	7% 5% 2 6% 5% 5% 6% 5% 7% 9% 44%	5862
	11th to 20th	Day	10% 6% 2 6% 4 4 4 4 6% 9% 44%	5861
	21st to end	Day	4 3 2 5% 5% 5% 6% 5% 8% 11% 47%	6433
June	1st to 10th	Day	10% 6% 3 9% 7% 7% 7% 5% 7% 10% 30%	2600
	11th to 20th	Day	5% 5% 2 7% 8% 7% 9% 7% 9% 11% 30%	2600
	21st to end	Day	8% 6% 2 7% 7% 7% 7% 6% 8% 11% 30%	2600
July	1st to 10th	Day	8% 6% 4 10% 7% 8% 9% 7% 11% 12% 19%	5900
	11th to 20th	Day	4 3 2 6% 5% 6% 7% 6% 10% 16% 35%	5900
	21st to end	Day	5% 5% 2 7% 6% 7% 7% 7% 10% 14% 31%	6424
August	1st to 10th	Day	12% 5% 2 8% 6% 7% 7% 6% 8% 12% 26%	4234
	11th to 20th	Day	7% 5% 2 6% 6% 6% 7% 5% 8% 12% 35%	3946
	21st to end	Day	10% 6% 3 9% 7% 7% 5% 5% 8% 10% 30%	4050
September	1st to 10th	Day	10% 7% 4 9% 8% 8% 7% 5% 7% 11% 25%	2200
	11th to 20th	Day	11% 7% 3 9% 6% 7% 8% 5% 8% 9% 26%	2200
	21st to end	Day	9% 8% 2 8% 6% 5% 5% 5% 6% 7% 39%	2200
October	1st to 10th	Day	11% 7% 3 7% 4 5% 5% 4 6% 7% 40%	2200
	11th to 20th	Day	6% 4 2 5% 4 4 4 3 5% 7% 57%	2034
	21st to end	Day	8% 5% 2 5% 4 4 4 5% 5% 8% 53%	2200
November	1st to 10th	Day	9% 4 1 5% 4 4 4 4 6% 7% 52%	2057
	11th to 20th	Day	8% 6% 3 5% 4 3 4 3 5% 6% 53%	1978
	21st to end	Day	10% 6% 2 4 4 4 5% 4 6% 7% 49%	1800
December	1st to 10th	Day	5% 4 2 6% 4 4 4 3 5% 7% 55%	2930
	11th to 20th	Day	12% 6% 2 6% 4 4 4 3 6% 7% 45%	3373
	21st to end	Day	16% 8% 3 7% 4 4 4 3 4 5% 42%	4466
January	1st to 10th	Night	10% 6% 2 4 2 2 3 2 4 6% 58%	5889
	11th to 20th	Night	16% 7% 2 7% 5% 5% 5% 4 6% 7% 35%	5900
	21st to end	Night	14% 7% 2 6% 3 3 4 3 6% 9% 43%	6260
February	1st to 10th	Night	14% 6% 2 7% 4 3 4 3 4 6% 47%	2400
	11th to 20th	Night	13% 7% 2 5% 4 4 4 2 5% 7% 47%	2338
	21st to end	Night	12% 8% 2 5% 4 3 4 2 4 6% 49%	1975
March	1st to 10th	Night	16% 8% 3 7% 4 4 4 3 5% 6% 40%	4918
	11th to 20th	Night	7% 4 2 4 3 3 4 3 7% 10% 54%	4980
	21st to end	Night	10% 5% 2 5% 4 4 4 3 5% 7% 50%	5467
April	1st to 10th	Night	10% 5% 2 4 5% 4 4 4 5% 8% 49%	2200
	11th to 20th	Night	8% 5% 2 6% 3 4 4 3 6% 6% 52%	2173
	21st to end	Night	5% 5% 1 5% 3 4 4 3 7% 7% 56%	1864
May	1st to 10th	Night	7% 6% 2 6% 4 5% 5% 4 6% 9% 47%	4033
	11th to 20th	Night	10% 6% 2 6% 4 4 4 4 6% 10% 45%	4032
	21st to end	Night	4 3 1 4 3 4 4 4 6% 12% 55%	4421
June	1st to 10th	Night	9% 6% 3 7% 5% 5% 6% 4 8% 11% 34%	1800
	11th to 20th	Night	5% 4 2 6% 5% 6% 7% 6% 10% 13% 37%	1800
	21st to end	Night	7% 4 2 7% 5% 6% 7% 5% 9% 14% 35%	1800
July	1st to 10th	Night	8% 8% 4 11% 8% 7% 9% 6% 9% 11% 19%	4058
	11th to 20th	Night	3 4 2 6% 5% 6% 7% 7% 11% 15% 36%	4057
	21st to end	Night	6% 6% 3 9% 6% 6% 6% 6% 10% 13% 30%	4427
August	1st to 10th	Night	12% 5% 2 8% 6% 6% 7% 5% 8% 13% 29%	2915
	11th to 20th	Night	5% 3 2 5% 4 4 6% 5% 9% 15% 42%	3097
	21st to end	Night	9% 7% 4 8% 5% 6% 6% 5% 7% 10% 33%	3812
September	1st to 10th	Night	9% 8% 3 9% 6% 6% 6% 5% 8% 10% 29%	2200
	11th to 20th	Night	10% 6% 3 7% 6% 6% 6% 5% 8% 11% 31%	2200
	21st to end	Night	9% 5% 3 8% 5% 5% 5% 5% 6% 9% 42%	2200
October	1st to 10th	Night	9% 6% 3 7% 5% 4 4 3 5% 8% 44%	2200
	11th to 20th	Night	7% 4 1 5% 4 4 4 3 5% 6% 58%	2365
	21st to end	Night	8% 5% 2 6% 4 4 4 3 6% 7% 53%	2640
November	1st to 10th	Night	8% 4 2 5% 4 4 3 4 7% 7% 53%	2461
	11th to 20th	Night	10% 5% 2 6% 4 3 4 3 5% 6% 53%	2571
	21st to end	Night	11% 6% 2 6% 5% 4 3 4 6% 6% 48%	2600
December	1st to 10th	Night	10% 5% 2 5% 4 3 3 2 4 6% 55%	4250
	11th to 20th	Night	11% 7% 2 6% 4 4 4 3 5% 6% 47%	4822
	21st to end	Night	14% 8% 3 6% 4 4 4 3 5% 6% 41%	6490

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	30% 2 6% 16% 29% 16%	4057
	11th to 20th	Day	48% 2 4 13% 20% 13%	4060
	21st to end	Day	34% 2 10% 23% 18% 12%	4678
February	1st to 10th	Day	40% 2 10% 15% 22% 11%	2000
	11th to 20th	Day	39% 3 7% 16% 23% 12%	1958
	21st to end	Day	38% 3 8% 17% 21% 14%	1652
March	1st to 10th	Day	43% 3 9% 16% 19% 11%	4935
	11th to 20th	Day	28% 3 11% 16% 21% 21%	4980
	21st to end	Day	33% 3 9% 25% 18% 12%	5465
April	1st to 10th	Day	33% 4 12% 20% 20% 13%	2200
	11th to 20th	Day	36% 3 7% 21% 22% 11%	2176
	21st to end	Day	27% 4 10% 25% 25% 8%	2550
May	1st to 10th	Day	35% 6% 15% 25% 15% 4	5897
	11th to 20th	Day	37% 3 14% 31% 13% 1	5865
	21st to end	Day	30% 6% 16% 29% 18% 2	6447
June	1st to 10th	Day	47% 6% 18% 18% 10% 1	2600
	11th to 20th	Day	43% 7% 22% 20% 7%	2600
	21st to end	Day	44% 9% 24% 17% 6% 1	2600
July	1st to 10th	Day	50% 16% 26% 8% 1	5835
	11th to 20th	Day	31% 13% 41% 13% 1	5831
	21st to end	Day	36% 14% 28% 20% 2	6240
August	1st to 10th	Day	46% 10% 28% 14% 2	4221
	11th to 20th	Day	38% 8% 25% 21% 8%	3985
	21st to end	Day	45% 10% 22% 20% 3	4050
September	1st to 10th	Day	51% 8% 19% 13% 7% 2	2200
	11th to 20th	Day	50% 8% 16% 16% 8% 1	2200
	21st to end	Day	42% 6% 11% 20% 17% 4	2200
October	1st to 10th	Day	49% 5% 7% 12% 17% 10%	3590
	11th to 20th	Day	19% 2 5% 17% 39% 19%	3287
	21st to end	Day	21% 3 7% 19% 39% 11%	3538
November	1st to 10th	Day	31% 4 9% 21% 19% 16%	2057
	11th to 20th	Day	32% 3 8% 19% 25% 13%	1978
	21st to end	Day	35% 3 9% 20% 24% 9%	1800
December	1st to 10th	Day	29% 3 11% 20% 24% 13%	2930
	11th to 20th	Day	38% 4 7% 23% 19% 8%	3370
	21st to end	Day	45% 3 6% 18% 23% 5%	4466
January	1st to 10th	Night	29% 2 6% 14% 34% 15%	5889
	11th to 20th	Night	49% 2 6% 15% 20% 8%	5900
	21st to end	Night	40% 3 10% 18% 18% 11%	6260
February	1st to 10th	Night	39% 3 8% 16% 20% 13%	2400
	11th to 20th	Night	38% 3 7% 19% 19% 13%	2339
	21st to end	Night	38% 2 8% 19% 20% 13%	1975
March	1st to 10th	Night	46% 2 9% 16% 16% 11%	4918
	11th to 20th	Night	27% 2 12% 19% 21% 19%	4980
	21st to end	Night	34% 2 9% 21% 20% 13%	5467
April	1st to 10th	Night	32% 4 13% 20% 19% 11%	2200
	11th to 20th	Night	32% 4 9% 22% 22% 11%	2173
	21st to end	Night	27% 3 13% 28% 21% 8%	1864
May	1st to 10th	Night	35% 5% 18% 26% 12% 4	4060
	11th to 20th	Night	35% 4 19% 28% 12% 2	4033
	21st to end	Night	23% 5% 20% 32% 19% 2	4429
June	1st to 10th	Night	42% 6% 21% 22% 8% 1	1800
	11th to 20th	Night	34% 12% 26% 22% 6%	1800
	21st to end	Night	36% 11% 26% 20% 6% 1	1800
July	1st to 10th	Night	55% 15% 22% 7% 1	4015
	11th to 20th	Night	33% 14% 40% 12% 2	4006
	21st to end	Night	42% 13% 26% 18% 1	4297
August	1st to 10th	Night	44% 11% 31% 12% 2	2904
	11th to 20th	Night	28% 11% 31% 22% 8%	3124
	21st to end	Night	43% 10% 23% 19% 4	3812
September	1st to 10th	Night	47% 10% 22% 15% 6% 1	2200
	11th to 20th	Night	44% 10% 18% 18% 8% 1	2200
	21st to end	Night	37% 5% 18% 20% 15% 4	2200
October	1st to 10th	Night	48% 6% 11% 14% 12% 9%	3590
	11th to 20th	Night	20% 3 5% 22% 32% 18%	3851
	21st to end	Night	22% 3 7% 21% 34% 13%	4252
November	1st to 10th	Night	30% 4 9% 24% 19% 14%	2461
	11th to 20th	Night	33% 3 8% 19% 23% 14%	2571
	21st to end	Night	36% 4 9% 20% 21% 11%	2600
December	1st to 10th	Night	33% 2 9% 20% 19% 17%	4250
	11th to 20th	Night	39% 4 9% 21% 18% 9%	4824
	21st to end	Night	44% 3 9% 18% 21% 5%	6490

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	10% 13% 47% 20% 9% 1	300
	11th to 20th	Day	14% 9% 36% 27% 11% 3	300
	21st to end	Day	15% 14% 46% 20% 5%	330
February	1st to 10th	Day	16% 12% 34% 26% 10% 3	300
	11th to 20th	Day	19% 9% 38% 24% 9% 1	300
	21st to end	Day	10% 10% 41% 27% 11% 1	251
March	1st to 10th	Day	14% 9% 32% 29% 15% 1	500
	11th to 20th	Day	15% 6% 30% 32% 14% 3	500
	21st to end	Day	13% 7% 32% 28% 19% 2	550
April	1st to 10th	Day	10% 9% 28% 31% 18% 4	500
	11th to 20th	Day	10% 7% 28% 31% 18% 6%	492
	21st to end	Day	6% 4 20% 35% 24% 11%	500
May	1st to 10th	Day	6% 5% 19% 30% 26% 14%	503
	11th to 20th	Day	7% 3 16% 26% 28% 19%	527
	21st to end	Day	10% 1 9% 20% 32% 27%	573
June	1st to 10th	Day	12% 3 7% 23% 28% 27%	530
	11th to 20th	Day	7% 2 9% 18% 31% 34%	530
	21st to end	Day	7% 2 3 19% 31% 38%	530
July	1st to 10th	Day	7% 3 3 14% 30% 44%	525
	11th to 20th	Day	6% 1 1 12% 35% 44%	524
	21st to end	Day	9% 2 3 12% 33% 40%	576
August	1st to 10th	Day	13% 3 4 15% 28% 38%	526
	11th to 20th	Day	8% 1 3 13% 30% 46%	519
	21st to end	Day	11% 3 3 17% 33% 32%	583
September	1st to 10th	Day	12% 3 7% 19% 29% 30%	530
	11th to 20th	Day	14% 2 7% 27% 32% 18%	530
	21st to end	Day	11% 3 6% 23% 36% 20%	530
October	1st to 10th	Day	15% 5% 18% 32% 20% 10%	530
	11th to 20th	Day	7% 4 17% 30% 31% 11%	530
	21st to end	Day	10% 3 19% 39% 24% 5%	583
November	1st to 10th	Day	12% 4 19% 35% 23% 6%	535
	11th to 20th	Day	14% 5% 28% 36% 14% 4	436
	21st to end	Day	11% 8% 31% 32% 15% 3	300
December	1st to 10th	Day	10% 9% 34% 24% 18% 4	300
	11th to 20th	Day	17% 7% 33% 30% 12% 1	300
	21st to end	Day	16% 8% 30% 32% 12% 3	330
January	1st to 10th	Night	17% 7% 33% 35% 9% 1	800
	11th to 20th	Night	14% 8% 26% 37% 15% 1	800
	21st to end	Night	20% 7% 33% 34% 7%	880
February	1st to 10th	Night	16% 5% 29% 38% 12% 1	800
	11th to 20th	Night	16% 7% 32% 36% 8%	783
	21st to end	Night	15% 6% 30% 43% 6%	660
March	1st to 10th	Night	12% 6% 32% 38% 11%	800
	11th to 20th	Night	12% 7% 29% 37% 15% 1	800
	21st to end	Night	12% 5% 30% 39% 13% 1	880
April	1st to 10th	Night	12% 6% 29% 39% 15% 1	800
	11th to 20th	Night	11% 5% 28% 39% 16% 1	791
	21st to end	Night	7% 3 21% 43% 25% 1	654
May	1st to 10th	Night	7% 3 15% 50% 24% 2	600
	11th to 20th	Night	8% 2 15% 43% 28% 5%	591
	21st to end	Night	8% 2 7% 38% 40% 6%	650
June	1st to 10th	Night	10% 1 8% 35% 39% 7%	600
	11th to 20th	Night	6% 2 5% 29% 42% 17%	600
	21st to end	Night	8% 2 5% 22% 47% 17%	600
July	1st to 10th	Night	8% 2 2 19% 49% 20%	585
	11th to 20th	Night	6% 1 1 12% 53% 26%	582
	21st to end	Night	6% 2 1 17% 55% 19%	657
August	1st to 10th	Night	10% 1 1 15% 55% 18%	597
	11th to 20th	Night	6% 2 1 13% 55% 23%	594
	21st to end	Night	13% 3 5% 22% 42% 16%	795
September	1st to 10th	Night	12% 2 6% 23% 44% 13%	800
	11th to 20th	Night	14% 2 5% 32% 39% 8%	800
	21st to end	Night	12% 1 9% 33% 39% 7%	800
October	1st to 10th	Night	14% 2 16% 40% 27% 3	800
	11th to 20th	Night	9% 2 16% 40% 30% 2	800
	21st to end	Night	8% 2 19% 43% 25% 2	880
November	1st to 10th	Night	10% 2 23% 42% 22% 1	820
	11th to 20th	Night	13% 3 22% 43% 18% 1	829
	21st to end	Night	13% 3 26% 42% 15% 1	800
December	1st to 10th	Night	15% 3 24% 37% 19% 2	800
	11th to 20th	Night	14% 4 26% 39% 17% 1	800
	21st to end	Night	16% 5% 26% 38% 15%	880

Page generated at 2025-11-15 00:56:00. Version ac07

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