Stub Stewart State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Stub Stewart State Park clear sky chart from 2005-11-06 to 2025-04-11.

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	18% 11% 3 7% 5% 4 4 3 5% 6% 34%	118127
	Night	19% 11% 3 7% 4 4 4 3 4 5% 35%	118938
Transparency	Day	52% 4 11% 18% 12% 4	117867
	Night	51% 3 12% 19% 11% 3	118787
Seeing	Day	22% 11% 26% 25% 13% 3	15487
	Night	22% 6% 22% 33% 15% 2	24158

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	33% 18% 5% 10% 6% 5% 5% 3 4 3 9%	3639
	11th to 20th	Day	23% 12% 4 8% 5% 4 4 3 5% 6% 27%	3640
	21st to end	Day	24% 12% 3 8% 5% 4 4 3 4 4 30%	4400
February	1st to 10th	Day	25% 17% 5% 9% 6% 5% 5% 3 4 6% 16%	1800
	11th to 20th	Day	27% 19% 5% 9% 5% 4 4 3 4 3 17%	1755
	21st to end	Day	26% 18% 5% 9% 6% 5% 4 3 4 4 16%	1540
March	1st to 10th	Day	17% 18% 4 12% 6% 6% 6% 4 5% 5% 17%	4777
	11th to 20th	Day	24% 19% 5% 8% 5% 4 3 2 2 3 25%	5000
	21st to end	Day	24% 18% 4 11% 7% 6% 5% 4 5% 5% 11%	5568
April	1st to 10th	Day	26% 16% 5% 9% 5% 5% 4 4 5% 6% 16%	2400
	11th to 20th	Day	24% 16% 4 8% 5% 4 4 3 4 4 23%	2277
	21st to end	Day	23% 13% 4 7% 6% 5% 5% 5% 6% 5% 22%	2470
May	1st to 10th	Day	20% 11% 3 7% 5% 4 4 3 5% 6% 33%	4327
	11th to 20th	Day	11% 6% 2 6% 5% 4 5% 4 6% 8% 42%	4377
	21st to end	Day	20% 10% 3 8% 7% 6% 7% 5% 6% 6% 23%	4813
June	1st to 10th	Day	21% 10% 3 7% 6% 5% 4 3 5% 6% 31%	2660
	11th to 20th	Day	18% 9% 3 8% 5% 5% 6% 5% 7% 8% 25%	2751
	21st to end	Day	10% 7% 2 5% 4 4 4 3 6% 8% 47%	2850
July	1st to 10th	Day	5% 4 1 4 3 3 3 2 4 5% 68%	4649
	11th to 20th	Day	5% 2 1 2 2 2 2 2 3 5% 72%	4420
	21st to end	Day	7% 4 1 3 2 2 3 2 4 6% 65%	4790
August	1st to 10th	Day	4 3 1 3 3 2 2 3 4 6% 67%	4102
	11th to 20th	Day	6% 5% 2 6% 5% 6% 6% 4 6% 8% 46%	4026
	21st to end	Day	9% 7% 3 6% 4 4 4 4 5% 6% 49%	4340
September	1st to 10th	Day	7% 4 2 4 3 4 3 3 5% 7% 57%	2280
	11th to 20th	Day	13% 7% 2 7% 5% 4 5% 4 6% 7% 41%	2258
	21st to end	Day	16% 7% 2 6% 4 4 4 3 4 6% 44%	2010
October	1st to 10th	Day	14% 6% 2 5% 3 4 3 3 5% 8% 48%	3180
	11th to 20th	Day	18% 8% 4 10% 6% 5% 6% 4 6% 6% 28%	3161
	21st to end	Day	25% 12% 3 8% 4 4 4 4 5% 6% 24%	3393
November	1st to 10th	Day	27% 14% 4 9% 5% 6% 5% 4 4 5% 16%	1622
	11th to 20th	Day	31% 13% 5% 9% 4 4 4 3 3 4 19%	1600
	21st to end	Day	25% 13% 5% 9% 6% 5% 3 3 6% 4 21%	1600
December	1st to 10th	Day	18% 12% 3 7% 5% 5% 5% 4 4 5% 33%	2620
	11th to 20th	Day	32% 18% 5% 9% 5% 5% 4 3 4 4 12%	3028
	21st to end	Day	31% 20% 6% 12% 6% 5% 4 3 3 3 8%	4004
January	1st to 10th	Night	32% 16% 4 9% 6% 5% 5% 3 4 4 12%	6306
	11th to 20th	Night	20% 13% 4 9% 5% 4 3 3 4 5% 30%	6320
	21st to end	Night	27% 12% 3 6% 3 3 2 2 3 4 33%	6556
February	1st to 10th	Night	22% 18% 4 8% 6% 5% 5% 4 4 5% 19%	2600
	11th to 20th	Night	24% 15% 4 8% 5% 4 5% 4 4 5% 24%	2532
	21st to end	Night	21% 16% 4 9% 6% 4 5% 4 4 5% 21%	2090
March	1st to 10th	Night	14% 16% 4 10% 7% 8% 7% 4 5% 5% 22%	5112
	11th to 20th	Night	20% 18% 4 8% 4 4 3 2 3 4 29%	5000
	21st to end	Night	26% 19% 3 9% 6% 5% 5% 3 5% 6% 13%	5407
April	1st to 10th	Night	22% 15% 4 8% 5% 6% 5% 3 4 5% 23%	2000
	11th to 20th	Night	18% 14% 3 8% 6% 4 4 4 5% 6% 29%	1854
	21st to end	Night	18% 12% 2 7% 5% 5% 4 4 5% 7% 32%	1710
May	1st to 10th	Night	19% 8% 2 5% 4 4 3 3 5% 5% 42%	2620
	11th to 20th	Night	8% 5% 2 5% 3 4 4 4 5% 8% 53%	2516
	21st to end	Night	10% 9% 3 7% 6% 6% 6% 4 6% 7% 36%	2762
June	1st to 10th	Night	16% 7% 3 6% 6% 4 3 3 5% 6% 40%	1520
	11th to 20th	Night	13% 8% 2 6% 5% 4 4 4 6% 8% 41%	1421
	21st to end	Night	7% 5% 1 5% 3 3 4 2 5% 5% 60%	1330
July	1st to 10th	Night	2 2 1 2 2 2 3 2 3 5% 76%	2306
	11th to 20th	Night	3 3 1 2 2 2 2 2 3 4 76%	2540
	21st to end	Night	3 1 1 2 2 3 3 2 3 5% 76%	2761
August	1st to 10th	Night	2 2 1 2 1 2 2 2 4 5% 78%	2834
	11th to 20th	Night	6% 4 2 4 2 3 4 4 5% 7% 61%	2812
	21st to end	Night	9% 5% 1 5% 3 2 3 2 4 5% 60%	3331
September	1st to 10th	Night	5% 4 1 3 3 3 3 2 4 6% 66%	1900
	11th to 20th	Night	9% 5% 3 5% 4 4 5% 3 5% 6% 51%	1919
	21st to end	Night	10% 6% 2 5% 4 4 4 3 5% 7% 52%	2169
October	1st to 10th	Night	10% 5% 1 4 3 4 4 3 5% 8% 53%	3800
	11th to 20th	Night	14% 9% 3 7% 4 4 4 4 6% 8% 35%	3777
	21st to end	Night	24% 11% 3 7% 4 5% 5% 3 4 5% 29%	4172
November	1st to 10th	Night	27% 11% 4 9% 5% 5% 4 3 4 6% 23%	2673
	11th to 20th	Night	31% 12% 3 7% 5% 5% 5% 4 4 5% 20%	2800
	21st to end	Night	24% 12% 4 8% 5% 4 4 4 4 5% 27%	2800
December	1st to 10th	Night	15% 11% 4 6% 4 4 4 3 5% 6% 38%	4560
	11th to 20th	Night	34% 18% 5% 9% 5% 5% 4 3 3 4 12%	5176
	21st to end	Night	32% 19% 5% 10% 5% 4 4 3 3 3 13%	6952

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	79% 2 7% 8% 3	3639
	11th to 20th	Day	57% 4 8% 20% 9% 2	3640
	21st to end	Day	59% 3 6% 13% 15% 4	4400
February	1st to 10th	Day	71% 3 11% 12% 4	1800
	11th to 20th	Day	72% 3 8% 10% 6% 1	1764
	21st to end	Day	73% 2 9% 8% 6% 1	1540
March	1st to 10th	Day	67% 4 12% 12% 5%	4777
	11th to 20th	Day	66% 2 7% 20% 6%	5000
	21st to end	Day	75% 5% 10% 8% 2	5568
April	1st to 10th	Day	70% 2 12% 13% 2	2400
	11th to 20th	Day	66% 2 9% 14% 8% 2	2280
	21st to end	Day	63% 3 12% 14% 6% 1	2470
May	1st to 10th	Day	54% 1 10% 23% 12%	4327
	11th to 20th	Day	39% 2 20% 27% 11% 1	4380
	21st to end	Day	61% 3 19% 14% 3	4814
June	1st to 10th	Day	56% 2 16% 17% 9%	2660
	11th to 20th	Day	56% 4 17% 16% 6%	2751
	21st to end	Day	36% 3 19% 28% 10% 3	2850
July	1st to 10th	Day	20% 2 9% 17% 21% 30%	4577
	11th to 20th	Day	16% 2 6% 22% 37% 16%	4345
	21st to end	Day	18% 4 12% 29% 32% 5%	4639
August	1st to 10th	Day	19% 2 10% 27% 29% 13%	4086
	11th to 20th	Day	31% 10% 17% 25% 13% 4	4065
	21st to end	Day	34% 6% 11% 24% 20% 5%	4339
September	1st to 10th	Day	26% 2 14% 28% 20% 10%	2280
	11th to 20th	Day	41% 5% 13% 21% 15% 6%	2258
	21st to end	Day	42% 3 14% 21% 16% 4	2010
October	1st to 10th	Day	34% 4 9% 30% 21% 2	3180
	11th to 20th	Day	53% 7% 13% 14% 12% 1	3161
	21st to end	Day	57% 6% 10% 17% 10% 1	3393
November	1st to 10th	Day	70% 3 10% 14% 4	1622
	11th to 20th	Day	70% 2 10% 11% 6% 2	1600
	21st to end	Day	65% 3 8% 12% 12% 1	1600
December	1st to 10th	Day	51% 5% 8% 15% 20%	2620
	11th to 20th	Day	76% 3 9% 10% 2	3028
	21st to end	Day	80% 4 8% 6% 2	4004
January	1st to 10th	Night	76% 2 8% 9% 5% 1	6306
	11th to 20th	Night	55% 4 9% 20% 11% 2	6320
	21st to end	Night	58% 1 6% 14% 15% 5%	6556
February	1st to 10th	Night	67% 3 10% 14% 5% 1	2600
	11th to 20th	Night	63% 3 11% 14% 7% 2	2534
	21st to end	Night	65% 3 12% 12% 7% 1	2090
March	1st to 10th	Night	61% 5% 12% 16% 6%	5112
	11th to 20th	Night	59% 4 12% 19% 6%	5000
	21st to end	Night	72% 4 12% 10% 1	5407
April	1st to 10th	Night	64% 3 13% 15% 5%	2000
	11th to 20th	Night	55% 4 13% 17% 8% 3	1854
	21st to end	Night	53% 3 16% 19% 7% 2	1710
May	1st to 10th	Night	45% 1 12% 30% 11% 1	2620
	11th to 20th	Night	29% 2 17% 34% 15% 2	2516
	21st to end	Night	46% 5% 29% 16% 4	2762
June	1st to 10th	Night	46% 3 17% 24% 8% 1	1520
	11th to 20th	Night	41% 3 21% 27% 8%	1421
	21st to end	Night	26% 2 22% 34% 11% 5%	1330
July	1st to 10th	Night	12% 2 12% 20% 22% 32%	2269
	11th to 20th	Night	15% 1 8% 22% 32% 23%	2492
	21st to end	Night	11% 3 13% 32% 32% 9%	2674
August	1st to 10th	Night	11% 1 12% 29% 31% 16%	2826
	11th to 20th	Night	20% 6% 26% 31% 12% 5%	2839
	21st to end	Night	26% 4 17% 25% 23% 4	3331
September	1st to 10th	Night	21% 3 15% 29% 22% 11%	1900
	11th to 20th	Night	34% 4 15% 24% 15% 8%	1919
	21st to end	Night	33% 3 17% 22% 18% 7%	2169
October	1st to 10th	Night	28% 5% 11% 34% 20% 2	3800
	11th to 20th	Night	45% 5% 17% 20% 10% 2	3777
	21st to end	Night	53% 6% 10% 20% 10% 1	4172
November	1st to 10th	Night	63% 4 10% 15% 7%	2673
	11th to 20th	Night	67% 3 11% 11% 7% 1	2800
	21st to end	Night	60% 3 11% 12% 12% 2	2800
December	1st to 10th	Night	45% 5% 9% 20% 20%	4560
	11th to 20th	Night	77% 4 8% 8% 4	5176
	21st to end	Night	77% 3 9% 9% 2	6952

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	41% 14% 22% 14% 8% 3	200
	11th to 20th	Day	35% 7% 26% 15% 13% 5%	200
	21st to end	Day	33% 9% 18% 23% 14% 3	395
February	1st to 10th	Day	35% 11% 27% 17% 9% 2	400
	11th to 20th	Day	37% 14% 27% 14% 7% 1	395
	21st to end	Day	37% 16% 22% 19% 5% 1	359
March	1st to 10th	Day	32% 15% 28% 18% 6%	500
	11th to 20th	Day	33% 15% 23% 19% 8% 2	500
	21st to end	Day	34% 14% 24% 17% 9% 1	550
April	1st to 10th	Day	33% 14% 21% 21% 9% 3	500
	11th to 20th	Day	29% 16% 28% 15% 7% 4	453
	21st to end	Day	28% 12% 30% 19% 10% 2	460
May	1st to 10th	Day	18% 17% 28% 21% 12% 4	463
	11th to 20th	Day	24% 10% 27% 22% 12% 4	488
	21st to end	Day	20% 10% 26% 28% 13% 4	529
June	1st to 10th	Day	22% 10% 26% 27% 13% 1	490
	11th to 20th	Day	18% 17% 35% 23% 6% 1	581
	21st to end	Day	8% 12% 33% 30% 14% 3	680
July	1st to 10th	Day	10% 7% 30% 35% 13% 5%	621
	11th to 20th	Day	7% 10% 27% 35% 17% 3	484
	21st to end	Day	4 6% 25% 41% 20% 4	531
August	1st to 10th	Day	7% 6% 24% 37% 21% 6%	487
	11th to 20th	Day	5% 4 23% 35% 25% 7%	477
	21st to end	Day	8% 7% 31% 31% 17% 5%	539
September	1st to 10th	Day	8% 8% 27% 36% 19% 3	490
	11th to 20th	Day	14% 8% 24% 31% 18% 6%	490
	21st to end	Day	18% 12% 24% 29% 14% 3	490
October	1st to 10th	Day	22% 9% 21% 27% 18% 3	490
	11th to 20th	Day	22% 9% 24% 24% 18% 4	490
	21st to end	Day	31% 12% 24% 18% 11% 4	508
November	1st to 10th	Day	31% 13% 26% 19% 9% 1	227
	11th to 20th	Day	33% 13% 23% 18% 8% 6%	200
	21st to end	Day	25% 12% 24% 21% 16% 3	200
December	1st to 10th	Day	30% 8% 24% 22% 13% 4	200
	11th to 20th	Day	39% 8% 26% 18% 9% 1	200
	21st to end	Day	36% 15% 18% 20% 10% 1	220
January	1st to 10th	Night	36% 7% 20% 22% 13% 2	800
	11th to 20th	Night	33% 6% 17% 25% 17% 2	800
	21st to end	Night	30% 5% 14% 31% 17% 3	880
February	1st to 10th	Night	27% 8% 22% 28% 14% 1	800
	11th to 20th	Night	30% 8% 18% 29% 15% 1	784
	21st to end	Night	29% 7% 20% 32% 11%	660
March	1st to 10th	Night	25% 9% 22% 30% 13% 1	800
	11th to 20th	Night	28% 7% 19% 33% 13% 1	800
	21st to end	Night	30% 10% 21% 27% 11% 1	880
April	1st to 10th	Night	27% 9% 22% 28% 13% 1	800
	11th to 20th	Night	24% 7% 25% 32% 11% 1	724
	21st to end	Night	22% 6% 26% 32% 13% 1	570
May	1st to 10th	Night	15% 8% 31% 31% 13% 1	434
	11th to 20th	Night	13% 7% 27% 35% 17% 1	374
	21st to end	Night	15% 7% 28% 34% 16%	411
June	1st to 10th	Night	18% 4 29% 37% 11%	380
	11th to 20th	Night	13% 7% 33% 35% 11% 1	380
	21st to end	Night	8% 6% 33% 42% 11% 1	380
July	1st to 10th	Night	5% 4 32% 45% 13%	370
	11th to 20th	Night	4 6% 39% 39% 11%	368
	21st to end	Night	3 3 35% 44% 13%	416
August	1st to 10th	Night	4 3 27% 42% 22% 2	553
	11th to 20th	Night	6% 2 17% 48% 25% 2	564
	21st to end	Night	7% 4 28% 39% 20% 1	734
September	1st to 10th	Night	6% 5% 26% 45% 17% 1	760
	11th to 20th	Night	9% 4 20% 37% 26% 4	760
	21st to end	Night	12% 6% 21% 40% 19% 2	760
October	1st to 10th	Night	16% 4 23% 37% 18% 2	760
	11th to 20th	Night	19% 4 19% 32% 22% 4	760
	21st to end	Night	26% 6% 21% 27% 18% 2	836
November	1st to 10th	Night	30% 6% 16% 35% 13% 1	780
	11th to 20th	Night	35% 7% 16% 28% 12% 1	800
	21st to end	Night	27% 5% 18% 31% 17% 2	800
December	1st to 10th	Night	26% 6% 17% 33% 16% 2	800
	11th to 20th	Night	36% 8% 16% 27% 12% 1	800
	21st to end	Night	39% 8% 20% 23% 9% 1	880

Page generated at 2025-04-08 06:17:28. Version ac07

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