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 2026-08-15.

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	16% 10% 3 7% 5% 4 4 3 5% 6% 37%	153939
	Night	17% 11% 3 7% 4 4 4 3 4 6% 37%	145236
Transparency	Day	47% 5% 12% 20% 13% 4	148706
	Night	48% 4 12% 20% 12% 3	141482
Seeing	Day	21% 11% 26% 25% 13% 3	17296
	Night	22% 7% 23% 33% 15% 1	25693

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% 20% 5% 10% 6% 5% 4 3 3 3 8%	4722
	11th to 20th	Day	18% 10% 3 7% 4 3 4 3 5% 6% 38%	4740
	21st to end	Day	24% 12% 3 8% 5% 4 4 3 4 4 29%	5705
February	1st to 10th	Day	25% 17% 4 9% 6% 5% 5% 4 5% 6% 15%	1890
	11th to 20th	Day	27% 19% 5% 9% 5% 4 4 3 4 3 17%	1845
	21st to end	Day	25% 18% 5% 9% 6% 5% 4 3 4 3 17%	1615
March	1st to 10th	Day	17% 18% 5% 12% 6% 6% 6% 4 5% 5% 17%	4883
	11th to 20th	Day	25% 18% 5% 8% 5% 4 3 2 2 3 25%	5110
	21st to end	Day	24% 18% 4 11% 7% 5% 5% 4 5% 5% 11%	5691
April	1st to 10th	Day	25% 15% 5% 9% 5% 5% 4 4 5% 6% 17%	2520
	11th to 20th	Day	23% 15% 4 8% 5% 4 4 3 4 4 24%	2518
	21st to end	Day	21% 13% 4 7% 6% 5% 5% 4 5% 6% 24%	2730
May	1st to 10th	Day	12% 8% 3 6% 4 4 5% 4 6% 7% 42%	8024
	11th to 20th	Day	11% 10% 4 9% 6% 6% 6% 5% 7% 7% 30%	8160
	21st to end	Day	13% 8% 3 6% 5% 5% 5% 5% 7% 8% 35%	8992
June	1st to 10th	Day	20% 10% 3 7% 6% 4 4 3 5% 6% 33%	2940
	11th to 20th	Day	17% 9% 3 8% 5% 5% 6% 4 7% 8% 28%	3041
	21st to end	Day	10% 7% 2 6% 4 4 4 3 6% 7% 45%	3150
July	1st to 10th	Day	3 4 1 4 3 3 3 3 4 6% 65%	8644
	11th to 20th	Day	5% 3 1 2 2 2 2 2 3 5% 74%	8220
	21st to end	Day	4 3 1 3 3 2 3 3 5% 6% 65%	8922
August	1st to 10th	Day	4 4 2 4 3 3 3 3 5% 7% 62%	5919
	11th to 20th	Day	7% 4 2 6% 5% 5% 6% 5% 6% 7% 46%	5849
	21st to end	Day	9% 7% 2 5% 4 4 4 4 5% 7% 49%	6209
September	1st to 10th	Day	7% 4 2 4 4 4 3 4 5% 7% 56%	2400
	11th to 20th	Day	12% 7% 2 7% 5% 4 5% 4 6% 7% 43%	2377
	21st to end	Day	16% 6% 2 6% 4 3 4 3 4 6% 44%	2116
October	1st to 10th	Day	14% 6% 2 5% 3 4 3 3 5% 8% 47%	3280
	11th to 20th	Day	17% 8% 4 10% 6% 5% 6% 4 6% 6% 28%	3261
	21st to end	Day	25% 12% 4 8% 4 4 4 4 5% 6% 24%	3501
November	1st to 10th	Day	28% 14% 4 9% 6% 6% 5% 4 4 5% 16%	1705
	11th to 20th	Day	31% 13% 5% 9% 4 4 4 3 3 5% 19%	1680
	21st to end	Day	25% 13% 5% 9% 6% 5% 4 3 6% 4 21%	1680
December	1st to 10th	Day	19% 12% 3 7% 5% 5% 5% 3 4 5% 32%	2700
	11th to 20th	Day	32% 18% 5% 9% 5% 5% 4 3 4 4 12%	3108
	21st to end	Day	30% 20% 6% 12% 6% 5% 4 3 4 4 8%	4092
January	1st to 10th	Night	32% 17% 5% 10% 6% 5% 5% 3 4 4 11%	8172
	11th to 20th	Night	17% 11% 3 7% 4 3 3 2 4 5% 39%	8220
	21st to end	Night	25% 13% 3 7% 4 3 2 2 4 4 31%	8485
February	1st to 10th	Night	22% 17% 4 8% 6% 5% 5% 4 4 5% 20%	2730
	11th to 20th	Night	23% 15% 4 8% 5% 4 5% 4 4 5% 24%	2662
	21st to end	Night	21% 16% 4 9% 6% 4 5% 4 5% 5% 22%	2191
March	1st to 10th	Night	14% 16% 4 10% 7% 8% 7% 4 5% 5% 22%	5226
	11th to 20th	Night	20% 18% 4 8% 4 4 3 2 3 4 28%	5110
	21st to end	Night	26% 19% 3 9% 6% 5% 5% 3 5% 6% 14%	5526
April	1st to 10th	Night	21% 14% 4 8% 5% 6% 5% 3 5% 5% 24%	2100
	11th to 20th	Night	17% 13% 3 8% 6% 4 4 4 6% 6% 29%	2046
	21st to end	Night	17% 12% 2 7% 5% 5% 4 4 5% 7% 34%	1890
May	1st to 10th	Night	11% 6% 2 4 3 3 4 4 6% 7% 50%	4887
	11th to 20th	Night	9% 8% 3 8% 6% 6% 6% 5% 6% 8% 36%	4700
	21st to end	Night	8% 8% 3 6% 5% 5% 5% 4 6% 9% 42%	5181
June	1st to 10th	Night	15% 7% 3 6% 6% 4 3 4 5% 6% 41%	1680
	11th to 20th	Night	12% 7% 2 6% 5% 4 4 4 6% 8% 45%	1571
	21st to end	Night	7% 4 2 5% 3 3 4 3 5% 6% 58%	1470
July	1st to 10th	Night	2 1 1 2 2 3 4 3 5% 6% 72%	4296
	11th to 20th	Night	2 2 1 2 2 2 2 2 3 4 78%	4740
	21st to end	Night	2 2 1 3 2 3 3 2 4 6% 73%	5153
August	1st to 10th	Night	3 3 1 3 3 3 4 2 4 6% 68%	4096
	11th to 20th	Night	10% 4 2 4 2 3 4 4 5% 7% 56%	4088
	21st to end	Night	8% 5% 2 5% 4 3 4 3 5% 6% 56%	4778
September	1st to 10th	Night	6% 4 1 4 3 3 3 2 4 6% 64%	2000
	11th to 20th	Night	8% 5% 2 5% 4 4 4 4 5% 6% 52%	2020
	21st to end	Night	10% 6% 2 5% 4 4 4 3 5% 7% 52%	2283
October	1st to 10th	Night	10% 5% 2 4 3 4 4 3 5% 7% 53%	3920
	11th to 20th	Night	14% 9% 3 7% 4 4 4 4 6% 8% 35%	3897
	21st to end	Night	24% 11% 3 7% 4 5% 5% 3 4 5% 29%	4306
November	1st to 10th	Night	27% 11% 4 9% 5% 5% 4 3 4 6% 22%	2810
	11th to 20th	Night	31% 12% 3 7% 5% 5% 5% 3 4 5% 20%	2940
	21st to end	Night	24% 12% 4 8% 5% 4 4 4 4 5% 26%	2940
December	1st to 10th	Night	16% 12% 4 6% 4 4 4 3 5% 6% 37%	4700
	11th to 20th	Night	34% 18% 4 9% 5% 5% 4 3 3 4 12%	5316
	21st to end	Night	31% 19% 5% 10% 5% 4 4 3 3 3 13%	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	80% 3 6% 7% 3	4723
	11th to 20th	Day	46% 5% 7% 16% 16% 10%	4740
	21st to end	Day	58% 3 6% 13% 16% 3	5705
February	1st to 10th	Day	70% 3 12% 11% 4	1890
	11th to 20th	Day	72% 3 7% 11% 6% 1	1854
	21st to end	Day	72% 2 9% 9% 6% 1	1615
March	1st to 10th	Day	67% 4 12% 12% 5%	4883
	11th to 20th	Day	66% 2 6% 19% 5%	5110
	21st to end	Day	74% 5% 10% 9% 2	5691
April	1st to 10th	Day	68% 3 13% 14% 2	2520
	11th to 20th	Day	63% 3 9% 15% 8% 2	2521
	21st to end	Day	61% 4 12% 15% 7% 1	2730
May	1st to 10th	Day	39% 4 12% 31% 14%	8024
	11th to 20th	Day	45% 8% 18% 21% 7%	8163
	21st to end	Day	44% 6% 23% 22% 5%	8994
June	1st to 10th	Day	53% 3 16% 18% 10% 1	2940
	11th to 20th	Day	52% 4 17% 19% 8%	3041
	21st to end	Day	37% 4 18% 27% 11% 3	3150
July	1st to 10th	Day	18% 6% 12% 28% 19% 17%	8573
	11th to 20th	Day	14% 2 8% 23% 38% 14%	8145
	21st to end	Day	16% 6% 17% 36% 23% 3	8723
August	1st to 10th	Day	18% 3 10% 27% 29% 13%	4347
	11th to 20th	Day	31% 10% 17% 25% 13% 4	4248
	21st to end	Day	34% 6% 11% 24% 20% 5%	4476
September	1st to 10th	Day	27% 3 14% 28% 19% 10%	2400
	11th to 20th	Day	39% 5% 13% 21% 16% 6%	2377
	21st to end	Day	41% 3 14% 21% 17% 4	2116
October	1st to 10th	Day	34% 5% 9% 30% 20% 2	3280
	11th to 20th	Day	53% 7% 13% 15% 12% 1	3261
	21st to end	Day	57% 6% 10% 16% 10% 1	3501
November	1st to 10th	Day	70% 3 10% 13% 4	1705
	11th to 20th	Day	70% 2 10% 11% 5% 2	1680
	21st to end	Day	65% 4 8% 11% 11%	1680
December	1st to 10th	Day	52% 5% 8% 15% 19%	2700
	11th to 20th	Day	76% 3 9% 10% 2	3108
	21st to end	Day	79% 4 8% 6% 2	4092
January	1st to 10th	Night	75% 4 8% 8% 4 1	8172
	11th to 20th	Night	47% 4 8% 16% 18% 7%	8220
	21st to end	Night	57% 2 6% 12% 19% 4	8485
February	1st to 10th	Night	66% 4 10% 14% 5% 1	2730
	11th to 20th	Night	62% 3 11% 14% 7% 2	2664
	21st to end	Night	64% 3 11% 13% 7% 1	2191
March	1st to 10th	Night	61% 5% 12% 16% 6%	5226
	11th to 20th	Night	59% 4 12% 19% 6%	5110
	21st to end	Night	71% 4 12% 11% 2	5526
April	1st to 10th	Night	63% 3 14% 16% 5%	2100
	11th to 20th	Night	54% 5% 13% 17% 9% 2	2046
	21st to end	Night	51% 4 15% 21% 7% 2	1890
May	1st to 10th	Night	32% 4 12% 37% 15%	4885
	11th to 20th	Night	38% 10% 18% 25% 8% 1	4700
	21st to end	Night	36% 6% 29% 24% 4	5182
June	1st to 10th	Night	44% 4 17% 25% 9% 1	1680
	11th to 20th	Night	38% 3 19% 29% 10%	1571
	21st to end	Night	26% 3 22% 33% 11% 4	1470
July	1st to 10th	Night	9% 8% 13% 30% 21% 18%	4259
	11th to 20th	Night	11% 2 9% 25% 38% 16%	4692
	21st to end	Night	12% 4 17% 38% 24% 5%	5040
August	1st to 10th	Night	11% 2 12% 29% 31% 16%	3004
	11th to 20th	Night	20% 6% 25% 31% 12% 6%	2965
	21st to end	Night	26% 5% 16% 25% 23% 4	3436
September	1st to 10th	Night	22% 3 15% 28% 21% 11%	2000
	11th to 20th	Night	33% 4 15% 24% 16% 8%	2020
	21st to end	Night	32% 3 17% 23% 18% 7%	2283
October	1st to 10th	Night	28% 5% 11% 34% 19% 2	3920
	11th to 20th	Night	45% 6% 17% 21% 11% 1	3897
	21st to end	Night	53% 6% 10% 20% 10% 1	4306
November	1st to 10th	Night	64% 4 9% 15% 7%	2810
	11th to 20th	Night	67% 3 11% 11% 7% 1	2940
	21st to end	Night	61% 3 10% 12% 12% 2	2940
December	1st to 10th	Night	47% 5% 9% 20% 20%	4700
	11th to 20th	Night	77% 4 8% 8% 4	5316
	21st to end	Night	76% 3 9% 9% 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	41% 15% 21% 14% 7% 2	220
	11th to 20th	Day	32% 6% 27% 16% 14% 5%	220
	21st to end	Day	33% 9% 19% 23% 14% 2	426
February	1st to 10th	Day	33% 12% 28% 17% 8% 2	430
	11th to 20th	Day	36% 15% 27% 15% 6% 1	425
	21st to end	Day	37% 16% 23% 19% 5% 1	386
March	1st to 10th	Day	32% 16% 28% 18% 6%	540
	11th to 20th	Day	34% 16% 22% 18% 8% 2	540
	21st to end	Day	34% 14% 25% 17% 9% 1	594
April	1st to 10th	Day	31% 13% 21% 21% 11% 3	540
	11th to 20th	Day	27% 17% 28% 18% 7% 4	532
	21st to end	Day	26% 12% 29% 21% 10% 1	540
May	1st to 10th	Day	17% 16% 28% 24% 12% 3	543
	11th to 20th	Day	25% 14% 27% 20% 11% 4	568
	21st to end	Day	19% 10% 27% 28% 13% 4	617
June	1st to 10th	Day	21% 12% 27% 26% 12% 2	570
	11th to 20th	Day	16% 17% 36% 24% 6% 1	671
	21st to end	Day	8% 12% 33% 31% 13% 2	780
July	1st to 10th	Day	9% 7% 32% 35% 13% 4	715
	11th to 20th	Day	7% 9% 31% 34% 16% 3	564
	21st to end	Day	4 6% 25% 41% 20% 5%	619
August	1st to 10th	Day	7% 6% 25% 37% 20% 6%	567
	11th to 20th	Day	5% 4 24% 35% 25% 6%	534
	21st to end	Day	8% 8% 30% 33% 17% 5%	583
September	1st to 10th	Day	8% 8% 26% 37% 19% 3	530
	11th to 20th	Day	13% 8% 24% 32% 17% 6%	530
	21st to end	Day	18% 12% 25% 28% 14% 3	530
October	1st to 10th	Day	21% 9% 22% 28% 17% 3	530
	11th to 20th	Day	21% 11% 24% 23% 17% 4	530
	21st to end	Day	31% 13% 24% 18% 10% 4	550
November	1st to 10th	Day	32% 13% 26% 19% 8% 1	250
	11th to 20th	Day	33% 13% 23% 17% 8% 5%	220
	21st to end	Day	24% 14% 23% 21% 15% 3	220
December	1st to 10th	Day	33% 8% 22% 22% 12% 3	220
	11th to 20th	Day	40% 10% 24% 18% 8% 1	220
	21st to end	Day	35% 15% 19% 20% 10% 1	242
January	1st to 10th	Night	36% 8% 20% 22% 12% 2	840
	11th to 20th	Night	32% 6% 17% 26% 17% 1	840
	21st to end	Night	29% 6% 14% 31% 17% 3	924
February	1st to 10th	Night	26% 8% 22% 29% 13% 1	840
	11th to 20th	Night	30% 8% 19% 29% 15% 1	824
	21st to end	Night	29% 8% 21% 31% 11%	692
March	1st to 10th	Night	25% 9% 22% 30% 13% 1	840
	11th to 20th	Night	29% 7% 19% 32% 12% 1	840
	21st to end	Night	29% 12% 21% 27% 10% 1	924
April	1st to 10th	Night	25% 9% 22% 29% 13% 1	840
	11th to 20th	Night	23% 8% 26% 31% 11% 1	798
	21st to end	Night	21% 7% 28% 32% 13% 1	630
May	1st to 10th	Night	14% 8% 33% 31% 13% 1	480
	11th to 20th	Night	12% 8% 29% 34% 15% 1	414
	21st to end	Night	14% 7% 29% 34% 15%	455
June	1st to 10th	Night	17% 5% 31% 35% 10%	420
	11th to 20th	Night	12% 7% 37% 34% 10% 1	420
	21st to end	Night	8% 6% 35% 41% 10%	420
July	1st to 10th	Night	4 4 34% 45% 12%	410
	11th to 20th	Night	4 8% 42% 37% 10%	408
	21st to end	Night	3 3 37% 45% 12%	460
August	1st to 10th	Night	4 4 28% 41% 20% 2	611
	11th to 20th	Night	7% 2 18% 47% 24% 2	606
	21st to end	Night	7% 4 29% 40% 19% 1	773
September	1st to 10th	Night	6% 5% 26% 45% 16% 1	800
	11th to 20th	Night	9% 4 21% 37% 25% 4	800
	21st to end	Night	12% 6% 21% 41% 18% 2	800
October	1st to 10th	Night	17% 5% 22% 36% 18% 2	800
	11th to 20th	Night	19% 4 20% 33% 21% 4	800
	21st to end	Night	25% 6% 22% 27% 18% 2	880
November	1st to 10th	Night	30% 6% 16% 35% 12%	820
	11th to 20th	Night	35% 8% 17% 27% 12% 1	840
	21st to end	Night	27% 5% 18% 31% 16% 2	840
December	1st to 10th	Night	27% 6% 16% 32% 16% 2	840
	11th to 20th	Night	36% 9% 17% 26% 12% 1	840
	21st to end	Night	37% 9% 20% 23% 9% 1	924

Page generated at 2026-08-12 00:37:14. Version ac07

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