Eastman Lake Recreation Area
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Eastman Lake Recreation Area clear sky chart from 2005-11-06 to 2026-01-02.

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	6% 3 1 3 2 2 2 2 3 5% 71%	135624
	Night	8% 3 1 3 2 2 2 2 4 5% 67%	133206
Transparency	Day	18% 3 8% 18% 26% 27%	130639
	Night	22% 3 9% 19% 25% 22%	129169
Seeing	Day	7% 5% 17% 33% 28% 11%	16749
	Night	8% 2 12% 40% 30% 6%	26276

By Month

Percentage Cloud Cover SW (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 6% 4 3 4 3 5% 7% 49%	3647
	11th to 20th	Day	10% 4 2 6% 4 4 4 3 3 5% 55%	3980
	21st to end	Day	14% 6% 2 6% 4 4 4 4 5% 6% 45%	4510
February	1st to 10th	Day	15% 5% 2 4 3 3 4 4 5% 7% 48%	1862
	11th to 20th	Day	12% 5% 2 4 3 3 4 4 6% 7% 50%	1950
	21st to end	Day	15% 5% 2 5% 4 3 4 3 4 6% 50%	1650
March	1st to 10th	Day	15% 6% 2 5% 4 4 4 5% 8% 9% 38%	4518
	11th to 20th	Day	14% 4 2 4 3 3 3 3 5% 6% 55%	4970
	21st to end	Day	14% 4 2 4 3 3 3 4 5% 8% 50%	5827
April	1st to 10th	Day	10% 4 1 4 3 2 3 2 5% 6% 59%	2400
	11th to 20th	Day	8% 4 1 3 3 3 3 3 4 6% 61%	2369
	21st to end	Day	6% 3 1 2 3 3 3 3 4 6% 66%	2400
May	1st to 10th	Day	4 3 1 2 2 1 1 1 2 4 80%	5523
	11th to 20th	Day	2 1 1 1 1 2 2 3 4 82%	5962
	21st to end	Day	2 1 1 1 1 1 2 3 3 84%	6902
June	1st to 10th	Day	2 2 1 2 2 2 2 2 4 6% 75%	2800
	11th to 20th	Day	1 1 1 1 1 2 1 2 4 87%	2800
	21st to end	Day	1 1 1 1 1 1 1 2 2 2 87%	2800
July	1st to 10th	Day	1 1 1 2 94%	6319
	11th to 20th	Day	1 1 1 1 1 1 1 2 2 89%	6320
	21st to end	Day	1 1 1 1 1 2 3 4 87%	6455
August	1st to 10th	Day	1 1 1 1 1 1 1 1 2 90%	5568
	11th to 20th	Day	1 1 2 94%	5364
	21st to end	Day	1 1 1 1 1 2 1 3 3 85%	5984
September	1st to 10th	Day	1 1 1 1 1 1 1 2 2 89%	2400
	11th to 20th	Day	2 1 2 2 1 1 1 2 5% 82%	2365
	21st to end	Day	2 1 1 1 1 1 2 1 2 4 83%	2200
October	1st to 10th	Day	2 2 1 2 2 2 2 2 4 4 79%	3352
	11th to 20th	Day	3 1 1 2 1 2 2 1 3 3 81%	3261
	21st to end	Day	3 2 1 4 2 2 3 3 4 6% 69%	3558
November	1st to 10th	Day	7% 3 1 2 3 3 3 3 4 8% 62%	1860
	11th to 20th	Day	10% 4 2 3 3 2 3 3 5% 6% 59%	1890
	21st to end	Day	10% 4 2 3 3 3 3 4 5% 7% 58%	1890
December	1st to 10th	Day	8% 4 1 4 3 4 4 3 5% 7% 56%	2768
	11th to 20th	Day	18% 6% 3 6% 4 4 3 4 5% 7% 41%	3108
	21st to end	Day	15% 8% 3 7% 5% 5% 6% 5% 6% 9% 31%	4092
January	1st to 10th	Night	11% 6% 2 4 3 3 3 3 4 8% 53%	6320
	11th to 20th	Night	13% 5% 2 4 2 3 3 3 4 5% 56%	5990
	21st to end	Night	15% 5% 2 5% 3 3 3 2 4 6% 51%	6468
February	1st to 10th	Night	16% 5% 2 4 3 2 3 3 4 6% 51%	2535
	11th to 20th	Night	13% 4 1 4 2 3 3 3 4 7% 56%	2338
	21st to end	Night	15% 5% 2 4 2 2 2 3 4 6% 53%	1980
March	1st to 10th	Night	16% 5% 2 5% 4 4 5% 4 5% 6% 44%	5376
	11th to 20th	Night	13% 5% 2 5% 3 3 3 3 4 5% 54%	5027
	21st to end	Night	18% 5% 2 3 3 2 3 3 4 7% 50%	5148
April	1st to 10th	Night	10% 4 1 4 2 3 2 3 5% 7% 60%	2000
	11th to 20th	Night	6% 3 1 2 3 3 4 3 6% 6% 64%	1979
	21st to end	Night	6% 3 1 3 2 2 3 2 4 6% 69%	2000
May	1st to 10th	Night	2 2 1 2 2 2 2 2 3 4 80%	4469
	11th to 20th	Night	2 1 1 1 1 2 2 3 4 82%	3941
	21st to end	Night	1 1 2 1 1 1 1 2 3 87%	3972
June	1st to 10th	Night	3 2 1 2 2 2 2 2 4 6% 75%	1600
	11th to 20th	Night	1 1 1 1 1 2 2 3 89%	1600
	21st to end	Night	1 1 1 1 1 2 2 2 2 87%	1600
July	1st to 10th	Night	1 1 96%	3640
	11th to 20th	Night	1 1 1 1 1 2 1 2 2 86%	3640
	21st to end	Night	1 1 1 1 1 1 1 2 3 88%	4413
August	1st to 10th	Night	1 1 1 1 1 1 1 2 3 88%	4251
	11th to 20th	Night	1 1 1 1 1 1 2 93%	4506
	21st to end	Night	2 1 1 1 1 2 1 2 3 85%	5015
September	1st to 10th	Night	1 1 1 1 1 1 2 2 90%	2000
	11th to 20th	Night	2 1 1 2 1 1 2 2 2 4 82%	2035
	21st to end	Night	2 1 2 1 1 2 2 2 4 83%	2200
October	1st to 10th	Night	2 1 1 1 1 1 1 2 3 3 83%	3845
	11th to 20th	Night	3 1 2 1 1 1 1 3 3 83%	3897
	21st to end	Night	4 3 1 3 2 2 2 2 3 5% 76%	4253
November	1st to 10th	Night	8% 3 1 3 2 2 2 2 4 6% 67%	2657
	11th to 20th	Night	7% 3 1 4 2 2 2 2 5% 7% 63%	2730
	21st to end	Night	9% 3 2 3 2 3 3 3 5% 7% 59%	2730
December	1st to 10th	Night	8% 3 1 4 3 3 3 3 5% 6% 62%	4629
	11th to 20th	Night	16% 6% 2 5% 4 3 3 3 6% 9% 42%	5316
	21st to end	Night	14% 7% 3 8% 6% 5% 5% 5% 7% 7% 33%	7106

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	33% 6% 23% 21% 13% 3	3647
	11th to 20th	Day	32% 6% 9% 15% 23% 16%	3980
	21st to end	Day	39% 6% 11% 15% 25% 4	4510
February	1st to 10th	Day	35% 5% 11% 24% 18% 6%	1862
	11th to 20th	Day	32% 5% 11% 25% 21% 6%	1960
	21st to end	Day	35% 6% 11% 27% 19% 3	1650
March	1st to 10th	Day	38% 7% 14% 19% 19% 3	4518
	11th to 20th	Day	31% 4 16% 28% 12% 8%	4970
	21st to end	Day	32% 6% 14% 30% 15% 3	5827
April	1st to 10th	Day	27% 4 12% 29% 21% 8%	2400
	11th to 20th	Day	24% 5% 10% 28% 24% 10%	2372
	21st to end	Day	20% 4 10% 29% 29% 7%	2400
May	1st to 10th	Day	13% 2 6% 24% 40% 16%	5523
	11th to 20th	Day	8% 1 4 29% 42% 15%	5965
	21st to end	Day	8% 1 5% 21% 48% 17%	6904
June	1st to 10th	Day	12% 3 9% 21% 32% 23%	2800
	11th to 20th	Day	5% 1 4 15% 36% 38%	2800
	21st to end	Day	6% 1 2 7% 30% 54%	2800
July	1st to 10th	Day	2 1 1 3 14% 80%	6251
	11th to 20th	Day	5% 1 2 3 13% 77%	6245
	21st to end	Day	5% 1 2 8% 35% 50%	6268
August	1st to 10th	Day	8% 1 2 5% 24% 61%	4052
	11th to 20th	Day	3 2 4 25% 66%	3880
	21st to end	Day	5% 1 2 6% 28% 58%	4311
September	1st to 10th	Day	6% 1 3 7% 27% 56%	2400
	11th to 20th	Day	9% 1 3 19% 39% 30%	2365
	21st to end	Day	8% 2 3 17% 37% 33%	2200
October	1st to 10th	Day	10% 2 4 11% 20% 53%	3352
	11th to 20th	Day	11% 1 4 22% 40% 21%	3261
	21st to end	Day	18% 2 5% 17% 40% 18%	3558
November	1st to 10th	Day	22% 4 12% 26% 27% 11%	1860
	11th to 20th	Day	26% 4 14% 27% 23% 6%	1890
	21st to end	Day	28% 4 11% 22% 26% 9%	1890
December	1st to 10th	Day	27% 5% 10% 29% 22% 7%	2768
	11th to 20th	Day	43% 4 12% 21% 16% 4	3108
	21st to end	Day	47% 9% 18% 18% 6% 2	4092
January	1st to 10th	Night	31% 5% 23% 23% 15% 2	6320
	11th to 20th	Night	31% 5% 12% 14% 28% 9%	5990
	21st to end	Night	36% 4 10% 21% 22% 7%	6468
February	1st to 10th	Night	34% 4 10% 23% 21% 8%	2535
	11th to 20th	Night	29% 3 11% 28% 23% 6%	2339
	21st to end	Night	33% 3 11% 29% 19% 5%	1980
March	1st to 10th	Night	39% 5% 11% 20% 21% 4	5376
	11th to 20th	Night	34% 3 14% 26% 15% 6%	5027
	21st to end	Night	35% 4 17% 25% 16% 3	5148
April	1st to 10th	Night	25% 3 14% 29% 20% 8%	2000
	11th to 20th	Night	22% 3 12% 29% 25% 9%	1979
	21st to end	Night	18% 4 12% 31% 30% 6%	2000
May	1st to 10th	Night	10% 2 8% 29% 36% 14%	4466
	11th to 20th	Night	8% 1 5% 28% 44% 14%	3942
	21st to end	Night	7% 1 4 22% 53% 13%	3972
June	1st to 10th	Night	13% 3 8% 24% 33% 20%	1600
	11th to 20th	Night	4 2 4 16% 36% 38%	1600
	21st to end	Night	5% 1 2 8% 25% 58%	1600
July	1st to 10th	Night	1 1 1 2 13% 83%	3600
	11th to 20th	Night	7% 1 1 3 11% 77%	3592
	21st to end	Night	5% 1 1 6% 36% 51%	4288
August	1st to 10th	Night	8% 1 2 6% 20% 63%	3085
	11th to 20th	Night	4 1 2 4 20% 70%	3256
	21st to end	Night	6% 1 5% 25% 62%	3608
September	1st to 10th	Night	4 1 2 8% 25% 60%	2000
	11th to 20th	Night	10% 1 3 14% 40% 32%	2035
	21st to end	Night	9% 1 3 14% 37% 36%	2200
October	1st to 10th	Night	9% 1 3 10% 20% 56%	3845
	11th to 20th	Night	10% 2 4 22% 41% 22%	3897
	21st to end	Night	14% 1 4 18% 38% 24%	4253
November	1st to 10th	Night	21% 2 9% 26% 25% 16%	2657
	11th to 20th	Night	22% 3 11% 28% 24% 11%	2730
	21st to end	Night	25% 4 10% 24% 28% 9%	2730
December	1st to 10th	Night	24% 3 13% 29% 23% 8%	4629
	11th to 20th	Night	39% 5% 15% 19% 18% 4	5316
	21st to end	Night	47% 8% 15% 21% 6% 2	7106

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% 6% 21% 27% 19% 4	202
	11th to 20th	Day	14% 4 14% 34% 25% 9%	345
	21st to end	Day	15% 2 15% 33% 23% 12%	440
February	1st to 10th	Day	17% 8% 17% 27% 21% 10%	432
	11th to 20th	Day	14% 6% 23% 33% 17% 7%	495
	21st to end	Day	12% 7% 20% 37% 21% 3	414
March	1st to 10th	Day	17% 7% 22% 31% 19% 4	500
	11th to 20th	Day	15% 9% 24% 26% 20% 6%	500
	21st to end	Day	16% 9% 25% 25% 20% 4	550
April	1st to 10th	Day	12% 10% 24% 28% 19% 7%	500
	11th to 20th	Day	9% 11% 24% 32% 19% 5%	492
	21st to end	Day	5% 10% 24% 30% 21% 9%	500
May	1st to 10th	Day	5% 7% 27% 36% 17% 8%	503
	11th to 20th	Day	4 7% 27% 34% 22% 8%	528
	21st to end	Day	5% 7% 18% 34% 29% 8%	573
June	1st to 10th	Day	1 4 20% 34% 29% 11%	530
	11th to 20th	Day	2 4 21% 38% 26% 10%	530
	21st to end	Day	1 3 15% 36% 32% 13%	530
July	1st to 10th	Day	1 9% 37% 38% 15%	526
	11th to 20th	Day	1 1 5% 33% 44% 17%	524
	21st to end	Day	1 1 6% 36% 40% 16%	575
August	1st to 10th	Day	4 1 13% 37% 31% 14%	527
	11th to 20th	Day	1 1 13% 38% 33% 15%	517
	21st to end	Day	2 1 9% 32% 39% 18%	583
September	1st to 10th	Day	1 2 11% 35% 35% 15%	530
	11th to 20th	Day	3 2 21% 34% 28% 12%	530
	21st to end	Day	2 3 15% 34% 34% 13%	530
October	1st to 10th	Day	2 4 19% 30% 31% 14%	530
	11th to 20th	Day	5% 5% 16% 28% 32% 15%	530
	21st to end	Day	4 5% 14% 28% 36% 13%	583
November	1st to 10th	Day	9% 3 13% 26% 32% 18%	336
	11th to 20th	Day	10% 2 15% 34% 28% 11%	330
	21st to end	Day	11% 2 13% 33% 32% 8%	330
December	1st to 10th	Day	14% 2 10% 35% 25% 14%	242
	11th to 20th	Day	14% 4 12% 34% 24% 12%	220
	21st to end	Day	21% 4 18% 29% 21% 7%	242
January	1st to 10th	Night	18% 2 13% 35% 24% 9%	804
	11th to 20th	Night	12% 3 13% 39% 26% 8%	800
	21st to end	Night	17% 2 11% 39% 26% 6%	880
February	1st to 10th	Night	17% 4 13% 36% 22% 9%	800
	11th to 20th	Night	13% 4 14% 36% 25% 8%	784
	21st to end	Night	15% 4 12% 47% 18% 4	660
March	1st to 10th	Night	17% 3 17% 38% 22% 3	800
	11th to 20th	Night	14% 4 16% 35% 25% 6%	800
	21st to end	Night	14% 4 18% 38% 23% 2	880
April	1st to 10th	Night	10% 4 19% 39% 25% 3	800
	11th to 20th	Night	6% 6% 23% 39% 22% 5%	791
	21st to end	Night	6% 5% 21% 39% 23% 6%	800
May	1st to 10th	Night	4 4 20% 45% 22% 4	761
	11th to 20th	Night	5% 4 21% 44% 26%	537
	21st to end	Night	4 4 20% 41% 30% 1	433
June	1st to 10th	Night	4 5% 18% 47% 25% 2	400
	11th to 20th	Night	1 3 17% 53% 26% 1	400
	21st to end	Night	1 14% 54% 31% 1	400
July	1st to 10th	Night	7% 55% 37% 1	390
	11th to 20th	Night	2 5% 49% 42% 2	388
	21st to end	Night	1 1 4 34% 54% 6%	624
August	1st to 10th	Night	3 6% 46% 40% 5%	688
	11th to 20th	Night	7% 46% 41% 5%	792
	21st to end	Night	2 4 39% 49% 6%	880
September	1st to 10th	Night	1 5% 40% 48% 6%	800
	11th to 20th	Night	3 1 10% 42% 37% 8%	800
	21st to end	Night	2 1 9% 38% 40% 10%	800
October	1st to 10th	Night	4 1 10% 41% 37% 8%	800
	11th to 20th	Night	5% 1 10% 36% 38% 10%	800
	21st to end	Night	5% 1 10% 37% 32% 15%	880
November	1st to 10th	Night	9% 2 9% 34% 33% 13%	820
	11th to 20th	Night	8% 1 11% 43% 28% 9%	840
	21st to end	Night	10% 1 11% 38% 30% 9%	840
December	1st to 10th	Night	15% 2 10% 38% 28% 7%	840
	11th to 20th	Night	17% 3 8% 41% 27% 5%	840
	21st to end	Night	18% 3 13% 42% 19% 4	924

Page generated at 2025-12-29 22:14:11. Version ac07

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