Hartman Creek State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Hartman Creek State Park clear sky chart from 2005-11-06 to 2026-01-17.

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	13% 8% 3 7% 5% 4 5% 4 6% 7% 39%	127678
	Night	13% 9% 3 7% 5% 4 4 3 5% 7% 39%	124274
Transparency	Day	42% 6% 12% 25% 13% 1	131151
	Night	43% 6% 12% 23% 14% 2	128874
Seeing	Day	16% 11% 30% 26% 13% 4	17589
	Night	16% 10% 33% 30% 11% 1	27542

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	9% 10% 6% 13% 6% 5% 4 3 4 6% 34%	3697
	11th to 20th	Day	8% 12% 5% 9% 5% 5% 6% 5% 6% 8% 30%	3668
	21st to end	Day	12% 13% 6% 10% 4 5% 4 3 4 5% 34%	4046
February	1st to 10th	Day	9% 11% 6% 10% 5% 4 5% 3 6% 7% 34%	1800
	11th to 20th	Day	10% 12% 4 7% 5% 4 5% 4 5% 6% 38%	1861
	21st to end	Day	11% 11% 5% 10% 5% 5% 4 3 6% 7% 33%	1650
March	1st to 10th	Day	13% 7% 3 5% 3 3 3 3 5% 7% 48%	4480
	11th to 20th	Day	10% 7% 3 7% 4 4 4 4 6% 8% 43%	4768
	21st to end	Day	24% 11% 3 8% 4 3 4 3 4 5% 30%	5917
April	1st to 10th	Day	16% 13% 3 8% 5% 4 5% 3 5% 6% 32%	2400
	11th to 20th	Day	19% 10% 3 7% 5% 4 5% 4 4 5% 34%	2374
	21st to end	Day	18% 10% 3 8% 6% 4 4 4 5% 6% 32%	2510
May	1st to 10th	Day	14% 6% 2 6% 4 4 4 4 5% 6% 45%	6155
	11th to 20th	Day	13% 5% 2 6% 4 4 4 3 6% 8% 43%	6319
	21st to end	Day	16% 6% 3 6% 5% 5% 4 4 5% 7% 39%	6935
June	1st to 10th	Day	12% 5% 2 6% 5% 4 4 4 6% 8% 44%	2800
	11th to 20th	Day	15% 7% 2 6% 5% 5% 5% 3 7% 9% 38%	2800
	21st to end	Day	11% 6% 2 7% 5% 4 6% 4 6% 9% 40%	2800
July	1st to 10th	Day	11% 5% 2 6% 4 5% 6% 4 7% 10% 40%	6360
	11th to 20th	Day	6% 4 1 5% 4 4 5% 5% 7% 10% 50%	6360
	21st to end	Day	8% 6% 2 7% 5% 5% 5% 4 6% 7% 44%	6924
August	1st to 10th	Day	10% 4 2 7% 5% 5% 5% 5% 6% 8% 43%	4563
	11th to 20th	Day	13% 4 2 4 4 5% 5% 3 6% 9% 45%	4017
	21st to end	Day	11% 6% 3 7% 4 5% 5% 5% 6% 8% 41%	4312
September	1st to 10th	Day	11% 6% 2 6% 4 3 4 4 6% 7% 45%	2400
	11th to 20th	Day	11% 5% 2 6% 4 4 4 3 6% 7% 48%	2330
	21st to end	Day	12% 6% 3 8% 5% 4 4 4 6% 7% 41%	2200
October	1st to 10th	Day	13% 7% 2 6% 5% 5% 3 3 5% 7% 44%	2043
	11th to 20th	Day	17% 10% 3 8% 4 5% 4 3 5% 7% 33%	2000
	21st to end	Day	15% 9% 3 8% 5% 4 4 3 4 6% 38%	1980
November	1st to 10th	Day	12% 7% 2 6% 6% 4 4 4 5% 6% 43%	1852
	11th to 20th	Day	12% 12% 4 8% 6% 5% 5% 4 6% 5% 32%	1829
	21st to end	Day	15% 10% 4 8% 5% 4 4 4 4 7% 34%	1680
December	1st to 10th	Day	9% 11% 5% 8% 6% 5% 6% 4 7% 7% 32%	2690
	11th to 20th	Day	12% 16% 5% 10% 5% 5% 4 3 5% 6% 31%	3088
	21st to end	Day	20% 19% 7% 12% 5% 4 4 2 4 4 19%	4070
January	1st to 10th	Night	10% 10% 7% 11% 6% 3 3 3 4 5% 39%	6488
	11th to 20th	Night	10% 11% 4 10% 6% 6% 7% 5% 6% 7% 28%	6445
	21st to end	Night	10% 15% 6% 10% 5% 5% 4 3 5% 6% 31%	6927
February	1st to 10th	Night	10% 13% 5% 10% 5% 5% 4 4 5% 5% 35%	2600
	11th to 20th	Night	10% 9% 4 8% 5% 5% 4 4 5% 5% 40%	2425
	21st to end	Night	15% 11% 3 8% 5% 4 4 4 4 7% 35%	1980
March	1st to 10th	Night	14% 6% 2 6% 4 4 4 3 5% 7% 46%	5373
	11th to 20th	Night	10% 8% 3 7% 5% 5% 5% 4 6% 7% 41%	5220
	21st to end	Night	22% 10% 3 9% 5% 4 5% 3 4 5% 30%	5011
April	1st to 10th	Night	19% 11% 3 7% 5% 3 4 3 5% 6% 36%	2000
	11th to 20th	Night	20% 8% 2 6% 4 3 4 3 6% 6% 37%	1975
	21st to end	Night	17% 8% 3 5% 5% 4 4 4 5% 7% 39%	1890
May	1st to 10th	Night	14% 8% 2 7% 5% 4 4 3 5% 6% 41%	3737
	11th to 20th	Night	10% 5% 2 6% 4 4 5% 4 6% 8% 47%	3596
	21st to end	Night	18% 8% 3 7% 4 4 4 3 5% 6% 38%	3942
June	1st to 10th	Night	9% 4 2 7% 5% 4 5% 5% 6% 9% 45%	1600
	11th to 20th	Night	11% 7% 3 7% 4 5% 3 5% 6% 8% 41%	1600
	21st to end	Night	9% 6% 2 6% 5% 4 4 4 7% 7% 47%	1600
July	1st to 10th	Night	11% 5% 2 5% 4 5% 4 4 7% 10% 43%	3618
	11th to 20th	Night	8% 4 2 4 3 4 4 4 6% 7% 54%	3617
	21st to end	Night	6% 5% 2 6% 4 4 4 4 6% 8% 50%	3947
August	1st to 10th	Night	11% 5% 1 5% 5% 4 4 4 5% 7% 49%	2597
	11th to 20th	Night	10% 6% 2 7% 4 5% 5% 3 7% 8% 44%	3034
	21st to end	Night	10% 5% 2 5% 4 4 4 3 6% 7% 49%	3586
September	1st to 10th	Night	10% 4 2 4 4 3 3 3 6% 7% 53%	2000
	11th to 20th	Night	12% 4 2 5% 3 4 4 3 6% 6% 52%	2049
	21st to end	Night	12% 6% 2 6% 4 4 3 3 4 7% 48%	2200
October	1st to 10th	Night	11% 6% 2 6% 4 3 4 3 5% 7% 49%	2354
	11th to 20th	Night	15% 7% 2 7% 4 4 4 4 5% 7% 40%	2400
	21st to end	Night	17% 9% 2 8% 4 4 4 3 5% 6% 35%	2860
November	1st to 10th	Night	14% 8% 3 5% 4 3 3 3 5% 7% 44%	2666
	11th to 20th	Night	13% 11% 4 8% 5% 5% 4 3 5% 6% 36%	2788
	21st to end	Night	15% 10% 3 7% 5% 5% 4 3 6% 7% 36%	2940
December	1st to 10th	Night	9% 11% 3 7% 4 4 4 4 6% 9% 38%	4720
	11th to 20th	Night	13% 17% 7% 10% 5% 4 3 3 4 5% 29%	5339
	21st to end	Night	21% 17% 5% 10% 4 3 4 3 4 6% 23%	7150

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	51% 6% 12% 20% 10% 1	3698
	11th to 20th	Day	50% 7% 10% 17% 14% 2	3668
	21st to end	Day	53% 5% 11% 20% 11%	4046
February	1st to 10th	Day	49% 6% 13% 19% 11% 1	1800
	11th to 20th	Day	45% 7% 12% 25% 10% 2	1870
	21st to end	Day	50% 7% 13% 19% 10% 2	1650
March	1st to 10th	Day	37% 4 13% 24% 17% 6%	4480
	11th to 20th	Day	37% 5% 16% 25% 14% 2	4768
	21st to end	Day	57% 5% 8% 17% 12% 1	5919
April	1st to 10th	Day	52% 8% 10% 19% 10% 1	2400
	11th to 20th	Day	51% 6% 9% 20% 12% 2	2374
	21st to end	Day	51% 7% 11% 18% 10% 2	2510
May	1st to 10th	Day	38% 7% 12% 26% 15% 3	6191
	11th to 20th	Day	38% 7% 12% 27% 16% 1	6323
	21st to end	Day	42% 7% 9% 26% 15% 1	6949
June	1st to 10th	Day	37% 7% 14% 27% 15% 1	2800
	11th to 20th	Day	42% 7% 13% 25% 12% 1	2800
	21st to end	Day	39% 8% 15% 24% 13% 1	2800
July	1st to 10th	Day	37% 6% 15% 32% 8% 1	6291
	11th to 20th	Day	27% 7% 16% 35% 14% 1	6285
	21st to end	Day	37% 6% 13% 24% 18% 1	6728
August	1st to 10th	Day	37% 7% 16% 26% 13% 1	4548
	11th to 20th	Day	34% 8% 13% 34% 11%	4057
	21st to end	Day	39% 6% 14% 27% 13% 1	4311
September	1st to 10th	Day	36% 7% 14% 26% 16% 1	2400
	11th to 20th	Day	34% 8% 17% 30% 10% 1	2330
	21st to end	Day	40% 8% 13% 28% 11%	2200
October	1st to 10th	Day	25% 4 8% 38% 24% 1	3329
	11th to 20th	Day	40% 5% 10% 26% 17% 1	3240
	21st to end	Day	41% 4 15% 29% 11% 1	3180
November	1st to 10th	Day	41% 6% 14% 23% 15% 1	1852
	11th to 20th	Day	52% 6% 12% 20% 9% 1	1829
	21st to end	Day	50% 7% 14% 21% 6% 1	1680
December	1st to 10th	Day	50% 7% 15% 21% 6% 1	2690
	11th to 20th	Day	55% 5% 10% 18% 12% 1	3085
	21st to end	Day	69% 5% 6% 13% 7%	4070
January	1st to 10th	Night	49% 4 9% 24% 13% 1	6488
	11th to 20th	Night	53% 6% 10% 14% 16% 1	6445
	21st to end	Night	54% 6% 12% 17% 12%	6927
February	1st to 10th	Night	50% 5% 12% 20% 11% 2	2600
	11th to 20th	Night	45% 7% 11% 24% 11% 2	2426
	21st to end	Night	49% 6% 13% 19% 11% 2	1980
March	1st to 10th	Night	38% 6% 14% 25% 13% 4	5373
	11th to 20th	Night	41% 6% 16% 23% 13% 2	5220
	21st to end	Night	55% 5% 9% 17% 12% 1	5011
April	1st to 10th	Night	49% 6% 9% 17% 17% 1	2000
	11th to 20th	Night	46% 7% 9% 22% 14% 3	1975
	21st to end	Night	43% 7% 13% 22% 14% 1	1890
May	1st to 10th	Night	41% 7% 12% 18% 18% 4	3763
	11th to 20th	Night	33% 8% 15% 24% 18% 2	3597
	21st to end	Night	46% 7% 10% 23% 14% 1	3950
June	1st to 10th	Night	34% 8% 14% 27% 17% 1	1600
	11th to 20th	Night	40% 8% 12% 24% 15% 1	1600
	21st to end	Night	33% 8% 16% 26% 13% 4	1600
July	1st to 10th	Night	35% 6% 17% 29% 10% 3	3580
	11th to 20th	Night	28% 6% 15% 34% 16% 2	3572
	21st to end	Night	31% 6% 15% 25% 20% 2	3832
August	1st to 10th	Night	34% 6% 14% 27% 17% 1	2588
	11th to 20th	Night	36% 8% 14% 27% 14% 1	3060
	21st to end	Night	34% 6% 16% 23% 20% 2	3586
September	1st to 10th	Night	30% 7% 12% 30% 20% 1	2000
	11th to 20th	Night	32% 6% 13% 33% 15% 1	2049
	21st to end	Night	34% 7% 12% 30% 15% 1	2200
October	1st to 10th	Night	27% 4 7% 37% 23% 2	3848
	11th to 20th	Night	32% 6% 12% 31% 19% 1	3899
	21st to end	Night	46% 4 10% 24% 16%	4610
November	1st to 10th	Night	40% 6% 13% 25% 15% 2	2666
	11th to 20th	Night	48% 6% 14% 19% 11% 2	2788
	21st to end	Night	48% 7% 15% 22% 8% 1	2940
December	1st to 10th	Night	43% 6% 20% 22% 6% 3	4720
	11th to 20th	Night	59% 5% 10% 15% 11% 1	5341
	21st to end	Night	63% 5% 9% 15% 7%	7150

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	15% 13% 35% 26% 9% 2	330
	11th to 20th	Day	16% 15% 38% 23% 7% 1	318
	21st to end	Day	18% 11% 39% 26% 5%	330
February	1st to 10th	Day	14% 16% 40% 23% 6% 2	300
	11th to 20th	Day	17% 20% 38% 18% 7%	300
	21st to end	Day	16% 18% 44% 20% 2	249
March	1st to 10th	Day	18% 16% 39% 22% 5%	300
	11th to 20th	Day	21% 17% 32% 20% 8% 2	300
	21st to end	Day	26% 12% 31% 21% 8% 2	526
April	1st to 10th	Day	24% 17% 31% 23% 5%	500
	11th to 20th	Day	25% 17% 28% 18% 9% 3	492
	21st to end	Day	21% 15% 30% 20% 12% 2	500
May	1st to 10th	Day	18% 11% 33% 28% 9% 2	628
	11th to 20th	Day	17% 12% 30% 25% 12% 3	725
	21st to end	Day	18% 9% 28% 28% 12% 5%	789
June	1st to 10th	Day	11% 8% 32% 29% 16% 4	730
	11th to 20th	Day	17% 9% 30% 27% 13% 4	730
	21st to end	Day	13% 10% 29% 30% 15% 3	730
July	1st to 10th	Day	8% 4 21% 32% 26% 10%	721
	11th to 20th	Day	9% 6% 25% 34% 18% 9%	718
	21st to end	Day	7% 4 25% 34% 22% 7%	794
August	1st to 10th	Day	8% 4 27% 29% 23% 9%	726
	11th to 20th	Day	13% 5% 20% 27% 25% 10%	601
	21st to end	Day	11% 7% 23% 28% 23% 8%	583
September	1st to 10th	Day	14% 7% 26% 26% 19% 8%	530
	11th to 20th	Day	12% 4 20% 34% 22% 8%	530
	21st to end	Day	15% 11% 25% 24% 20% 5%	530
October	1st to 10th	Day	16% 11% 28% 24% 17% 4	373
	11th to 20th	Day	19% 19% 34% 20% 8%	330
	21st to end	Day	20% 15% 36% 22% 6% 1	363
November	1st to 10th	Day	14% 18% 35% 22% 9% 1	330
	11th to 20th	Day	17% 21% 35% 20% 6% 1	330
	21st to end	Day	22% 13% 45% 16% 5%	330
December	1st to 10th	Day	15% 15% 44% 19% 5% 1	330
	11th to 20th	Day	20% 18% 39% 17% 5% 1	330
	21st to end	Day	25% 17% 37% 17% 4 1	363
January	1st to 10th	Night	17% 13% 37% 26% 7% 1	1050
	11th to 20th	Night	18% 13% 38% 25% 5% 1	1031
	21st to end	Night	18% 11% 37% 27% 7%	1100
February	1st to 10th	Night	15% 13% 39% 27% 6%	1000
	11th to 20th	Night	15% 13% 42% 24% 6%	870
	21st to end	Night	21% 14% 38% 23% 4	660
March	1st to 10th	Night	17% 12% 35% 26% 9% 1	800
	11th to 20th	Night	15% 14% 39% 24% 8% 1	710
	21st to end	Night	21% 9% 30% 32% 7% 1	660
April	1st to 10th	Night	22% 11% 38% 23% 6%	600
	11th to 20th	Night	22% 11% 33% 28% 6% 1	593
	21st to end	Night	20% 9% 32% 31% 7% 1	600
May	1st to 10th	Night	21% 8% 33% 31% 7%	600
	11th to 20th	Night	17% 8% 33% 33% 8% 1	591
	21st to end	Night	16% 5% 26% 37% 16%	650
June	1st to 10th	Night	10% 6% 31% 41% 12% 1	600
	11th to 20th	Night	14% 5% 33% 37% 10% 1	600
	21st to end	Night	11% 6% 27% 41% 16% 1	600
July	1st to 10th	Night	7% 3 21% 44% 23% 2	585
	11th to 20th	Night	8% 5% 20% 43% 23% 2	582
	21st to end	Night	7% 2 23% 46% 21% 2	657
August	1st to 10th	Night	8% 3 17% 45% 25% 2	597
	11th to 20th	Night	9% 3 20% 35% 29% 3	594
	21st to end	Night	11% 3 21% 40% 23% 2	660
September	1st to 10th	Night	11% 5% 24% 37% 19% 5%	600
	11th to 20th	Night	13% 4 25% 31% 24% 3	649
	21st to end	Night	13% 8% 26% 34% 19% 1	800
October	1st to 10th	Night	13% 8% 30% 29% 18% 2	800
	11th to 20th	Night	18% 12% 33% 29% 8%	800
	21st to end	Night	20% 11% 32% 28% 7% 1	880
November	1st to 10th	Night	18% 10% 36% 25% 9% 1	820
	11th to 20th	Night	18% 15% 39% 23% 5%	898
	21st to end	Night	20% 14% 36% 24% 6%	1050
December	1st to 10th	Night	19% 13% 40% 22% 6%	1050
	11th to 20th	Night	21% 12% 38% 23% 5% 1	1050
	21st to end	Night	28% 11% 35% 22% 4	1155

Page generated at 2026-01-14 00:14:28. Version ac07

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