Tonopah Stargazing Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Tonopah Stargazing Park clear sky chart from 2005-11-06 to 2026-06-16.

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	2 3 1 3 2 2 3 3 4 6% 70%	145729
	Night	2 4 1 4 3 3 3 3 4 6% 67%	143719
Transparency	Day	15% 3 7% 17% 27% 31%	140728
	Night	18% 4 8% 19% 27% 24%	139702
Seeing	Day	5% 9% 21% 27% 24% 14%	17134
	Night	4 5% 21% 40% 26% 3	26746

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	4 7% 4 6% 3 3 4 3 4 6% 57%	4722
	11th to 20th	Day	1 3 1 3 2 3 3 2 4 5% 72%	4740
	21st to end	Day	3 5% 2 5% 3 3 3 3 6% 10% 57%	5766
February	1st to 10th	Day	3 5% 2 4 3 3 3 2 5% 7% 62%	2100
	11th to 20th	Day	3 5% 2 4 3 4 4 3 6% 8% 59%	2050
	21st to end	Day	2 5% 1 4 3 2 4 3 6% 8% 60%	1730
March	1st to 10th	Day	2 6% 2 6% 4 3 4 4 6% 10% 53%	4618
	11th to 20th	Day	2 6% 2 5% 3 4 4 4 5% 7% 58%	4835
	21st to end	Day	2 5% 2 5% 4 4 4 4 6% 9% 55%	5982
April	1st to 10th	Day	3 4 1 4 4 2 4 4 5% 7% 62%	2520
	11th to 20th	Day	2 3 2 3 3 3 3 3 5% 6% 66%	2489
	21st to end	Day	2 4 2 5% 3 3 3 2 4 7% 65%	2588
May	1st to 10th	Day	2 2 2 3 3 2 3 3 5% 5% 70%	7626
	11th to 20th	Day	2 2 1 2 2 2 2 2 3 4 77%	7596
	21st to end	Day	1 3 1 3 2 3 3 3 4 6% 70%	8498
June	1st to 10th	Day	2 3 1 4 3 3 3 3 5% 7% 67%	2940
	11th to 20th	Day	1 1 1 3 2 3 2 3 4 4 75%	2871
	21st to end	Day	1 2 1 2 2 2 2 2 3 3 79%	2800
July	1st to 10th	Day	1 1 1 2 1 1 1 1 2 3 85%	6319
	11th to 20th	Day	1 2 1 2 2 2 2 2 3 5% 78%	6320
	21st to end	Day	1 2 1 3 2 2 3 2 4 5% 75%	6673
August	1st to 10th	Day	2 2 1 2 1 2 1 1 2 3 85%	5612
	11th to 20th	Day	1 1 1 1 1 1 1 2 3 89%	5364
	21st to end	Day	1 2 1 3 2 2 3 2 4 5% 76%	5984
September	1st to 10th	Day	1 2 1 3 1 3 3 3 3 4 77%	2400
	11th to 20th	Day	2 2 1 2 1 1 2 2 3 4 79%	2225
	21st to end	Day	2 1 1 2 2 1 1 2 3 4 81%	2200
October	1st to 10th	Day	1 2 1 2 1 2 2 2 4 5% 78%	3600
	11th to 20th	Day	1 2 1 2 2 2 2 2 2 4 79%	3372
	21st to end	Day	1 3 1 2 2 1 2 2 3 5% 78%	3237
November	1st to 10th	Day	1 2 1 4 3 2 2 3 5% 8% 68%	1854
	11th to 20th	Day	2 4 1 3 2 3 3 2 4 7% 70%	1890
	21st to end	Day	2 4 1 4 3 2 3 3 5% 7% 66%	1890
December	1st to 10th	Day	1 3 1 3 2 2 3 4 5% 6% 70%	3040
	11th to 20th	Day	3 7% 2 5% 3 3 3 4 7% 10% 52%	3186
	21st to end	Day	2 5% 2 5% 3 3 4 5% 7% 9% 55%	4092
January	1st to 10th	Night	2 7% 4 8% 3 3 2 2 4 7% 58%	8172
	11th to 20th	Night	1 3 1 3 3 3 3 2 4 6% 72%	8220
	21st to end	Night	4 8% 2 5% 3 3 3 3 5% 7% 57%	8412
February	1st to 10th	Night	3 5% 2 5% 3 3 3 2 4 7% 63%	2520
	11th to 20th	Night	2 5% 1 4 4 3 3 3 6% 8% 60%	2458
	21st to end	Night	2 5% 2 5% 3 3 4 3 5% 8% 61%	2076
March	1st to 10th	Night	2 4 1 5% 4 4 4 4 5% 7% 60%	5496
	11th to 20th	Night	3 4 1 4 4 3 4 4 6% 8% 60%	5385
	21st to end	Night	2 5% 2 4 4 4 4 4 6% 7% 59%	5220
April	1st to 10th	Night	4 3 1 4 3 3 4 3 4 6% 65%	2100
	11th to 20th	Night	3 3 1 4 4 3 3 3 4 6% 68%	2079
	21st to end	Night	4 5% 1 4 4 3 3 3 5% 6% 64%	2031
May	1st to 10th	Night	3 3 2 4 3 3 3 2 4 6% 66%	5321
	11th to 20th	Night	2 2 1 3 2 2 3 2 4 6% 73%	5296
	21st to end	Night	4 4 2 5% 3 4 3 2 4 6% 62%	5684
June	1st to 10th	Night	2 2 1 3 3 3 3 3 6% 7% 66%	1680
	11th to 20th	Night	2 2 1 3 3 3 3 2 3 6% 73%	1640
	21st to end	Night	2 2 1 2 2 2 2 2 4 4 77%	1600
July	1st to 10th	Night	2 2 1 2 2 2 2 1 2 2 82%	3640
	11th to 20th	Night	2 3 1 4 2 3 4 3 6% 6% 66%	3640
	21st to end	Night	2 3 1 4 3 3 3 3 4 5% 69%	4183
August	1st to 10th	Night	2 2 1 3 2 2 3 2 3 4 75%	4204
	11th to 20th	Night	1 1 1 1 1 2 2 3 4 82%	4506
	21st to end	Night	2 3 1 4 3 3 3 3 4 6% 69%	5015
September	1st to 10th	Night	2 1 3 1 2 3 2 4 5% 76%	2000
	11th to 20th	Night	2 2 1 2 2 2 3 2 3 5% 77%	2173
	21st to end	Night	2 1 2 2 2 2 2 3 4 80%	2200
October	1st to 10th	Night	2 2 1 2 2 2 2 2 3 6% 77%	3600
	11th to 20th	Night	1 1 1 2 2 2 2 2 3 5% 79%	3769
	21st to end	Night	1 2 1 3 2 3 2 2 3 4 77%	4564
November	1st to 10th	Night	2 3 1 2 2 2 2 2 3 7% 74%	2665
	11th to 20th	Night	2 3 1 4 2 3 3 3 4 6% 70%	2730
	21st to end	Night	2 4 2 4 3 3 3 3 4 6% 67%	2730
December	1st to 10th	Night	1 3 1 3 3 3 4 3 5% 6% 69%	4370
	11th to 20th	Night	3 7% 1 3 2 3 3 3 6% 12% 56%	5234
	21st to end	Night	2 5% 2 6% 5% 5% 6% 5% 8% 11% 46%	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	28% 4 18% 26% 22% 3	4723
	11th to 20th	Day	14% 4 9% 19% 29% 24%	4740
	21st to end	Day	23% 4 11% 23% 28% 11%	5766
February	1st to 10th	Day	22% 4 12% 28% 24% 11%	2100
	11th to 20th	Day	22% 4 10% 27% 31% 8%	2060
	21st to end	Day	20% 4 13% 29% 25% 9%	1730
March	1st to 10th	Day	23% 5% 7% 24% 29% 11%	4618
	11th to 20th	Day	23% 4 11% 30% 25% 7%	4835
	21st to end	Day	21% 5% 12% 26% 26% 10%	5982
April	1st to 10th	Day	20% 4 8% 24% 27% 16%	2520
	11th to 20th	Day	17% 4 8% 20% 33% 18%	2492
	21st to end	Day	18% 3 8% 24% 34% 13%	2588
May	1st to 10th	Day	14% 4 5% 19% 38% 21%	7626
	11th to 20th	Day	11% 2 4 11% 41% 31%	7599
	21st to end	Day	14% 4 4 15% 37% 27%	8499
June	1st to 10th	Day	16% 3 7% 14% 29% 31%	2940
	11th to 20th	Day	11% 3 4 8% 26% 47%	2871
	21st to end	Day	10% 2 2 6% 20% 60%	2800
July	1st to 10th	Day	7% 1 1 3 10% 76%	6251
	11th to 20th	Day	10% 3 3 5% 12% 68%	6245
	21st to end	Day	12% 3 3 10% 18% 54%	6480
August	1st to 10th	Day	11% 2 2 7% 23% 55%	4086
	11th to 20th	Day	5% 1 2 5% 14% 73%	3880
	21st to end	Day	8% 1 2 5% 22% 61%	4311
September	1st to 10th	Day	11% 3 4 8% 23% 53%	2400
	11th to 20th	Day	10% 2 4 12% 30% 43%	2225
	21st to end	Day	9% 1 4 12% 33% 41%	2200
October	1st to 10th	Day	10% 2 4 10% 33% 42%	3600
	11th to 20th	Day	11% 2 2 12% 38% 34%	3372
	21st to end	Day	11% 2 3 19% 48% 17%	3237
November	1st to 10th	Day	14% 3 8% 26% 32% 16%	1854
	11th to 20th	Day	15% 3 9% 29% 35% 9%	1890
	21st to end	Day	17% 4 9% 28% 29% 13%	1890
December	1st to 10th	Day	15% 4 7% 26% 30% 18%	3040
	11th to 20th	Day	25% 6% 12% 28% 25% 4	3186
	21st to end	Day	23% 7% 20% 28% 19% 3	4092
January	1st to 10th	Night	27% 4 18% 27% 22% 3	8172
	11th to 20th	Night	15% 4 9% 20% 31% 21%	8220
	21st to end	Night	27% 5% 10% 23% 24% 12%	8412
February	1st to 10th	Night	22% 3 12% 27% 26% 10%	2520
	11th to 20th	Night	20% 5% 9% 26% 33% 8%	2459
	21st to end	Night	21% 5% 13% 28% 25% 9%	2076
March	1st to 10th	Night	20% 4 8% 21% 31% 15%	5496
	11th to 20th	Night	20% 5% 9% 32% 27% 7%	5385
	21st to end	Night	19% 5% 14% 29% 26% 7%	5220
April	1st to 10th	Night	19% 5% 9% 28% 26% 14%	2100
	11th to 20th	Night	17% 6% 7% 24% 30% 16%	2079
	21st to end	Night	21% 3 8% 25% 33% 10%	2031
May	1st to 10th	Night	17% 5% 6% 18% 37% 17%	5319
	11th to 20th	Night	12% 4 5% 11% 38% 28%	5297
	21st to end	Night	21% 4 6% 14% 34% 21%	5685
June	1st to 10th	Night	15% 5% 8% 14% 31% 27%	1680
	11th to 20th	Night	14% 4 3 11% 25% 44%	1640
	21st to end	Night	11% 3 3 7% 22% 55%	1600
July	1st to 10th	Night	10% 2 2 4 7% 75%	3600
	11th to 20th	Night	14% 5% 4 6% 15% 56%	3592
	21st to end	Night	16% 4 5% 9% 17% 50%	4064
August	1st to 10th	Night	18% 4 3 9% 24% 43%	3050
	11th to 20th	Night	7% 3 4 5% 12% 69%	3256
	21st to end	Night	9% 2 3 7% 17% 62%	3608
September	1st to 10th	Night	11% 2 4 10% 21% 50%	2000
	11th to 20th	Night	10% 3 5% 11% 27% 44%	2173
	21st to end	Night	10% 2 4 11% 30% 43%	2200
October	1st to 10th	Night	11% 3 4 11% 29% 43%	3600
	11th to 20th	Night	10% 2 3 13% 35% 37%	3769
	21st to end	Night	13% 2 2 16% 45% 22%	4564
November	1st to 10th	Night	12% 2 8% 27% 34% 17%	2665
	11th to 20th	Night	16% 4 7% 26% 34% 13%	2730
	21st to end	Night	19% 3 7% 24% 35% 12%	2730
December	1st to 10th	Night	16% 4 7% 22% 32% 19%	4370
	11th to 20th	Night	22% 4 15% 27% 28% 4	5234
	21st to end	Night	30% 6% 16% 26% 18% 3	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	13% 9% 26% 32% 14% 7%	220
	11th to 20th	Day	6% 10% 24% 29% 20% 12%	220
	21st to end	Day	6% 10% 21% 27% 22% 13%	409
February	1st to 10th	Day	7% 12% 30% 26% 15% 9%	540
	11th to 20th	Day	10% 12% 30% 25% 16% 6%	535
	21st to end	Day	4 14% 28% 34% 16% 4	446
March	1st to 10th	Day	6% 17% 29% 26% 16% 5%	540
	11th to 20th	Day	8% 16% 29% 23% 18% 7%	540
	21st to end	Day	6% 18% 31% 25% 15% 5%	594
April	1st to 10th	Day	7% 15% 24% 23% 20% 11%	540
	11th to 20th	Day	7% 18% 27% 29% 14% 5%	532
	21st to end	Day	5% 14% 28% 28% 13% 11%	540
May	1st to 10th	Day	6% 14% 28% 28% 15% 9%	543
	11th to 20th	Day	7% 14% 21% 27% 19% 11%	568
	21st to end	Day	5% 8% 18% 29% 24% 15%	617
June	1st to 10th	Day	3 6% 19% 28% 26% 18%	570
	11th to 20th	Day	4 8% 20% 29% 26% 14%	551
	21st to end	Day	2 5% 16% 28% 31% 18%	530
July	1st to 10th	Day	3 2 17% 29% 33% 15%	526
	11th to 20th	Day	2 2 8% 27% 39% 22%	524
	21st to end	Day	2 1 12% 30% 33% 22%	575
August	1st to 10th	Day	2 2 16% 34% 29% 17%	527
	11th to 20th	Day	2 3 16% 27% 28% 25%	517
	21st to end	Day	3 3 13% 26% 31% 24%	583
September	1st to 10th	Day	2 3 15% 27% 28% 24%	530
	11th to 20th	Day	3 5% 20% 27% 27% 17%	530
	21st to end	Day	3 5% 15% 28% 33% 15%	530
October	1st to 10th	Day	3 11% 21% 22% 23% 21%	530
	11th to 20th	Day	5% 8% 19% 25% 28% 15%	530
	21st to end	Day	4 6% 18% 26% 28% 18%	388
November	1st to 10th	Day	3 4 20% 28% 28% 16%	330
	11th to 20th	Day	6% 9% 17% 29% 24% 15%	330
	21st to end	Day	4 7% 18% 27% 28% 15%	330
December	1st to 10th	Day	5% 7% 19% 32% 27% 11%	330
	11th to 20th	Day	4 6% 26% 29% 24% 12%	247
	21st to end	Day	7% 10% 30% 26% 20% 7%	242
January	1st to 10th	Night	8% 6% 23% 37% 22% 5%	840
	11th to 20th	Night	3 3 24% 44% 22% 4	840
	21st to end	Night	7% 5% 23% 40% 22% 3	924
February	1st to 10th	Night	5% 6% 27% 36% 23% 3	840
	11th to 20th	Night	7% 7% 26% 38% 20% 3	824
	21st to end	Night	5% 5% 29% 45% 15% 2	692
March	1st to 10th	Night	3 10% 27% 44% 14% 2	840
	11th to 20th	Night	4 8% 26% 37% 22% 3	840
	21st to end	Night	5% 9% 30% 38% 16% 1	924
April	1st to 10th	Night	5% 10% 27% 38% 20% 1	840
	11th to 20th	Night	5% 11% 28% 38% 16% 3	831
	21st to end	Night	7% 10% 27% 36% 19% 3	771
May	1st to 10th	Night	5% 10% 31% 37% 16% 1	630
	11th to 20th	Night	6% 10% 27% 33% 22% 1	621
	21st to end	Night	7% 10% 26% 34% 22% 2	634
June	1st to 10th	Night	2 5% 20% 43% 27% 3	420
	11th to 20th	Night	2 5% 26% 45% 21% 1	410
	21st to end	Night	2 3 17% 48% 30% 1	400
July	1st to 10th	Night	3 1 9% 53% 33% 1	390
	11th to 20th	Night	3 2 7% 47% 39% 3	388
	21st to end	Night	3 2 6% 48% 40% 2	524
August	1st to 10th	Night	4 2 14% 49% 30% 1	667
	11th to 20th	Night	1 1 11% 42% 40% 4	792
	21st to end	Night	3 1 10% 42% 42% 2	880
September	1st to 10th	Night	3 3 11% 35% 44% 5%	800
	11th to 20th	Night	3 2 16% 37% 36% 6%	800
	21st to end	Night	2 4 14% 37% 38% 6%	800
October	1st to 10th	Night	3 4 18% 38% 32% 6%	800
	11th to 20th	Night	3 4 17% 38% 33% 6%	800
	21st to end	Night	1 3 20% 36% 31% 8%	880
November	1st to 10th	Night	2 5% 19% 35% 32% 7%	820
	11th to 20th	Night	4 3 21% 42% 25% 4	840
	21st to end	Night	4 4 19% 42% 27% 4	840
December	1st to 10th	Night	4 4 21% 47% 20% 5%	840
	11th to 20th	Night	7% 3 21% 45% 21% 2	840
	21st to end	Night	6% 6% 28% 41% 18% 2	924

Page generated at 2026-06-12 23:31:39. Version ac07

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