Cypress Creek Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Cypress Creek Park clear sky chart from 2005-11-06 to 2025-09-04.

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	12% 6% 2 6% 4 4 4 4 5% 7% 45%	125164
	Night	12% 6% 2 5% 4 4 4 3 5% 7% 50%	123739
Transparency	Day	37% 5% 10% 23% 19% 5%	128770
	Night	34% 4 10% 24% 22% 7%	128209
Seeing	Day	14% 7% 20% 26% 24% 10%	16531
	Night	15% 6% 22% 36% 20% 2	26249

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	17% 7% 3 6% 3 3 3 2 3 4 49%	4077
	11th to 20th	Day	9% 8% 2 6% 4 3 3 3 4 5% 52%	4080
	21st to end	Day	21% 7% 2 4 2 2 3 2 3 4 49%	4488
February	1st to 10th	Day	21% 9% 2 6% 3 3 2 3 3 5% 42%	1800
	11th to 20th	Day	16% 9% 3 6% 4 3 4 2 3 6% 43%	1863
	21st to end	Day	20% 8% 3 6% 4 4 3 3 4 5% 40%	1720
March	1st to 10th	Day	19% 9% 3 6% 4 3 3 3 4 5% 39%	4936
	11th to 20th	Day	10% 5% 2 5% 4 4 4 3 4 6% 53%	4980
	21st to end	Day	13% 8% 3 7% 4 4 4 4 5% 6% 43%	5462
April	1st to 10th	Day	13% 7% 2 6% 4 4 4 3 5% 6% 45%	2385
	11th to 20th	Day	15% 6% 2 5% 4 4 4 3 4 6% 46%	2374
	21st to end	Day	14% 6% 3 7% 5% 4 4 4 6% 7% 40%	2400
May	1st to 10th	Day	16% 8% 3 8% 5% 4 5% 4 5% 7% 36%	5423
	11th to 20th	Day	12% 6% 2 7% 5% 4 6% 4 6% 7% 39%	5862
	21st to end	Day	15% 7% 3 8% 5% 5% 5% 5% 6% 8% 33%	6434
June	1st to 10th	Day	8% 6% 2 6% 5% 5% 6% 4 6% 9% 43%	2697
	11th to 20th	Day	4 5% 2 5% 5% 6% 6% 5% 8% 11% 44%	2770
	21st to end	Day	4 3 1 4 4 6% 6% 5% 7% 9% 51%	2600
July	1st to 10th	Day	7% 5% 3 7% 5% 6% 7% 7% 8% 11% 35%	5900
	11th to 20th	Day	4 3 2 4 4 4 5% 4 7% 10% 51%	5900
	21st to end	Day	7% 7% 3 6% 5% 5% 5% 5% 7% 10% 40%	6422
August	1st to 10th	Day	4 3 1 3 3 3 5% 4 6% 8% 61%	4234
	11th to 20th	Day	9% 5% 2 7% 4 4 5% 4 8% 10% 41%	3911
	21st to end	Day	5% 4 2 5% 4 4 5% 4 7% 8% 51%	4312
September	1st to 10th	Day	11% 6% 2 5% 4 4 4 4 5% 7% 46%	2316
	11th to 20th	Day	14% 5% 2 5% 4 4 4 3 6% 8% 45%	2262
	21st to end	Day	10% 4 2 4 4 4 4 3 4 6% 53%	1989
October	1st to 10th	Day	6% 5% 2 4 4 3 3 4 5% 6% 58%	1900
	11th to 20th	Day	13% 4 1 5% 2 3 3 2 3 5% 57%	1900
	21st to end	Day	17% 5% 2 4 3 3 3 3 4 5% 52%	2090
November	1st to 10th	Day	13% 6% 1 4 3 3 2 3 4 6% 55%	1958
	11th to 20th	Day	9% 6% 2 5% 3 2 3 3 5% 7% 55%	1954
	21st to end	Day	17% 7% 3 4 4 4 3 2 4 6% 46%	1724
December	1st to 10th	Day	17% 7% 3 5% 3 3 3 3 3 4 48%	2610
	11th to 20th	Day	15% 10% 3 7% 5% 4 3 2 4 5% 42%	3008
	21st to end	Day	19% 7% 2 7% 5% 4 4 4 4 5% 39%	4423
January	1st to 10th	Night	16% 6% 2 5% 3 3 3 3 4 6% 48%	5888
	11th to 20th	Night	11% 5% 1 4 3 2 3 2 4 5% 59%	5900
	21st to end	Night	21% 7% 2 4 2 3 2 2 3 4 48%	6490
February	1st to 10th	Night	20% 8% 2 6% 4 3 3 3 4 5% 42%	2600
	11th to 20th	Night	17% 8% 3 6% 3 3 3 2 4 6% 44%	2421
	21st to end	Night	18% 7% 2 5% 3 3 3 2 3 5% 49%	1925
March	1st to 10th	Night	18% 7% 2 6% 4 4 3 3 4 5% 44%	4919
	11th to 20th	Night	11% 5% 2 6% 5% 3 3 3 4 6% 52%	4980
	21st to end	Night	12% 6% 2 7% 4 4 4 3 5% 8% 45%	5467
April	1st to 10th	Night	14% 5% 2 5% 3 3 3 3 6% 6% 50%	2015
	11th to 20th	Night	11% 5% 2 4 4 4 3 3 5% 7% 51%	1975
	21st to end	Night	13% 6% 2 6% 4 4 4 3 5% 7% 47%	2000
May	1st to 10th	Night	17% 7% 3 6% 4 5% 4 4 6% 7% 37%	4456
	11th to 20th	Night	16% 8% 3 7% 4 4 5% 4 6% 7% 37%	4053
	21st to end	Night	16% 8% 3 7% 4 4 4 3 4 6% 39%	4443
June	1st to 10th	Night	5% 4 2 4 3 3 4 4 7% 11% 52%	1689
	11th to 20th	Night	4 3 2 4 4 4 4 4 5% 9% 58%	1612
	21st to end	Night	3 2 1 4 4 4 4 3 6% 9% 62%	1800
July	1st to 10th	Night	6% 5% 3 7% 5% 5% 5% 5% 6% 10% 41%	4078
	11th to 20th	Night	3 3 1 5% 3 3 4 3 6% 10% 57%	4077
	21st to end	Night	4 5% 2 6% 4 4 6% 4 6% 11% 48%	4449
August	1st to 10th	Night	2 2 1 3 2 3 3 3 5% 8% 67%	2926
	11th to 20th	Night	4 3 1 4 4 4 4 4 7% 9% 56%	3138
	21st to end	Night	4 2 1 5% 4 4 5% 4 7% 10% 55%	3586
September	1st to 10th	Night	7% 5% 2 5% 3 4 3 3 5% 7% 55%	1930
	11th to 20th	Night	11% 5% 2 5% 3 4 4 4 5% 7% 51%	1913
	21st to end	Night	9% 4 1 4 2 2 4 4 4 7% 60%	2171
October	1st to 10th	Night	7% 3 1 4 3 3 3 3 5% 7% 61%	2280
	11th to 20th	Night	10% 4 2 4 3 3 3 2 3 4 62%	2280
	21st to end	Night	16% 5% 2 4 3 3 3 2 3 4 55%	2508
November	1st to 10th	Night	11% 5% 2 4 4 3 3 2 4 6% 56%	2340
	11th to 20th	Night	11% 5% 1 4 3 3 3 2 4 6% 58%	2442
	21st to end	Night	13% 6% 2 4 4 3 3 2 4 6% 52%	2673
December	1st to 10th	Night	15% 7% 2 5% 4 3 3 2 4 5% 50%	4580
	11th to 20th	Night	15% 8% 3 7% 4 4 3 2 3 4 46%	5199
	21st to end	Night	18% 8% 2 6% 4 4 4 3 4 5% 43%	6536

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	41% 3 9% 26% 20% 2	4078
	11th to 20th	Day	36% 3 8% 22% 26% 5%	4080
	21st to end	Day	41% 2 4 18% 25% 9%	4488
February	1st to 10th	Day	46% 5% 10% 21% 16% 4	1800
	11th to 20th	Day	45% 4 7% 20% 19% 5%	1872
	21st to end	Day	48% 5% 7% 14% 17% 9%	1720
March	1st to 10th	Day	47% 5% 5% 15% 15% 13%	4936
	11th to 20th	Day	32% 4 7% 18% 25% 13%	4980
	21st to end	Day	43% 4 8% 24% 20% 1	5464
April	1st to 10th	Day	39% 6% 9% 21% 21% 4	2385
	11th to 20th	Day	39% 5% 10% 21% 17% 7%	2374
	21st to end	Day	42% 6% 10% 21% 18% 2	2400
May	1st to 10th	Day	47% 5% 10% 23% 13% 1	5458
	11th to 20th	Day	42% 6% 13% 23% 15% 1	5866
	21st to end	Day	47% 8% 12% 17% 15% 2	6447
June	1st to 10th	Day	35% 9% 13% 24% 16% 2	2697
	11th to 20th	Day	31% 9% 15% 26% 18% 2	2770
	21st to end	Day	28% 8% 13% 28% 19% 4	2600
July	1st to 10th	Day	39% 6% 15% 28% 11% 1	5836
	11th to 20th	Day	27% 5% 15% 36% 16% 2	5831
	21st to end	Day	38% 5% 15% 28% 13%	6240
August	1st to 10th	Day	21% 5% 15% 30% 23% 6%	4220
	11th to 20th	Day	37% 6% 14% 31% 12% 1	3948
	21st to end	Day	29% 6% 11% 31% 20% 3	4311
September	1st to 10th	Day	36% 8% 11% 19% 19% 8%	2316
	11th to 20th	Day	36% 7% 12% 18% 22% 5%	2262
	21st to end	Day	32% 5% 9% 20% 27% 7%	1989
October	1st to 10th	Day	16% 3 5% 13% 38% 24%	3160
	11th to 20th	Day	19% 2 4 19% 38% 18%	3140
	21st to end	Day	32% 3 5% 29% 25% 6%	3428
November	1st to 10th	Day	32% 4 8% 25% 22% 8%	1958
	11th to 20th	Day	29% 4 9% 21% 27% 10%	1954
	21st to end	Day	41% 3 6% 19% 24% 5%	1724
December	1st to 10th	Day	42% 3 7% 27% 19% 3	2610
	11th to 20th	Day	45% 4 6% 21% 21% 4	3005
	21st to end	Day	46% 4 9% 23% 14% 4	4423
January	1st to 10th	Night	38% 3 8% 26% 23% 2	5888
	11th to 20th	Night	29% 4 8% 20% 31% 7%	5900
	21st to end	Night	42% 3 8% 17% 25% 6%	6490
February	1st to 10th	Night	45% 4 8% 20% 18% 5%	2600
	11th to 20th	Night	43% 4 7% 21% 19% 6%	2422
	21st to end	Night	39% 3 8% 18% 22% 9%	1925
March	1st to 10th	Night	42% 4 7% 14% 20% 13%	4919
	11th to 20th	Night	33% 4 6% 23% 18% 15%	4980
	21st to end	Night	38% 4 9% 25% 21% 3	5467
April	1st to 10th	Night	35% 5% 10% 23% 19% 9%	2015
	11th to 20th	Night	32% 6% 8% 24% 21% 9%	1975
	21st to end	Night	37% 5% 11% 23% 21% 3	2000
May	1st to 10th	Night	46% 6% 13% 21% 12% 2	4486
	11th to 20th	Night	45% 6% 13% 23% 12% 1	4054
	21st to end	Night	45% 6% 12% 20% 13% 5%	4452
June	1st to 10th	Night	24% 8% 15% 30% 21% 2	1689
	11th to 20th	Night	23% 6% 12% 31% 25% 2	1612
	21st to end	Night	20% 7% 13% 30% 24% 7%	1800
July	1st to 10th	Night	37% 5% 15% 27% 15% 1	4035
	11th to 20th	Night	22% 5% 14% 39% 18% 2	4026
	21st to end	Night	31% 5% 16% 29% 17% 1	4320
August	1st to 10th	Night	16% 5% 16% 34% 25% 5%	2916
	11th to 20th	Night	23% 5% 18% 36% 15% 2	3167
	21st to end	Night	23% 5% 13% 31% 24% 3	3586
September	1st to 10th	Night	27% 7% 10% 25% 22% 9%	1930
	11th to 20th	Night	32% 6% 10% 20% 26% 6%	1913
	21st to end	Night	25% 4 10% 21% 30% 9%	2171
October	1st to 10th	Night	16% 3 7% 14% 30% 30%	3800
	11th to 20th	Night	16% 3 4 15% 39% 23%	3779
	21st to end	Night	29% 2 4 24% 29% 12%	4120
November	1st to 10th	Night	31% 4 8% 22% 25% 10%	2340
	11th to 20th	Night	28% 4 7% 24% 26% 11%	2442
	21st to end	Night	34% 4 8% 21% 28% 6%	2673
December	1st to 10th	Night	38% 3 6% 32% 17% 4	4580
	11th to 20th	Night	44% 3 5% 21% 21% 7%	5201
	21st to end	Night	43% 4 9% 25% 15% 3	6536

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	24% 11% 30% 26% 7% 2	300
	11th to 20th	Day	23% 14% 36% 22% 4	300
	21st to end	Day	20% 13% 37% 22% 8%	330
February	1st to 10th	Day	28% 11% 34% 18% 8% 1	300
	11th to 20th	Day	25% 13% 39% 18% 5% 1	300
	21st to end	Day	31% 12% 34% 18% 5% 1	249
March	1st to 10th	Day	25% 12% 31% 23% 8%	300
	11th to 20th	Day	22% 18% 36% 20% 4	300
	21st to end	Day	21% 18% 38% 16% 6% 1	330
April	1st to 10th	Day	21% 12% 33% 23% 9% 2	485
	11th to 20th	Day	20% 13% 30% 26% 10% 1	492
	21st to end	Day	19% 9% 28% 29% 12% 2	500
May	1st to 10th	Day	18% 10% 27% 31% 14% 2	508
	11th to 20th	Day	15% 6% 22% 30% 22% 5%	725
	21st to end	Day	10% 5% 20% 35% 24% 7%	789
June	1st to 10th	Day	9% 5% 13% 27% 33% 13%	730
	11th to 20th	Day	6% 2 12% 29% 36% 14%	730
	21st to end	Day	4 2 12% 33% 33% 16%	730
July	1st to 10th	Day	6% 3 7% 25% 40% 18%	721
	11th to 20th	Day	5% 1 7% 30% 34% 23%	718
	21st to end	Day	7% 2 6% 22% 38% 24%	794
August	1st to 10th	Day	7% 2 6% 31% 40% 14%	726
	11th to 20th	Day	14% 2 7% 20% 38% 19%	557
	21st to end	Day	10% 2 5% 18% 39% 25%	583
September	1st to 10th	Day	12% 2 5% 23% 42% 17%	502
	11th to 20th	Day	12% 2 8% 23% 37% 18%	472
	21st to end	Day	14% 4 10% 32% 25% 14%	300
October	1st to 10th	Day	7% 3 19% 29% 33% 10%	300
	11th to 20th	Day	14% 6% 26% 33% 18% 4	300
	21st to end	Day	23% 10% 24% 27% 13% 4	330
November	1st to 10th	Day	20% 7% 30% 22% 18% 4	300
	11th to 20th	Day	12% 8% 30% 33% 13% 3	300
	21st to end	Day	23% 13% 24% 24% 15% 2	300
December	1st to 10th	Day	22% 9% 34% 20% 13% 2	300
	11th to 20th	Day	25% 12% 30% 21% 12%	300
	21st to end	Day	20% 16% 35% 25% 3 1	330
January	1st to 10th	Night	23% 8% 31% 34% 5%	1000
	11th to 20th	Night	19% 10% 35% 32% 5%	1000
	21st to end	Night	20% 7% 35% 34% 4	1100
February	1st to 10th	Night	25% 9% 31% 31% 4	1000
	11th to 20th	Night	22% 10% 35% 31% 1	866
	21st to end	Night	20% 10% 38% 30% 2	605
March	1st to 10th	Night	19% 8% 31% 37% 5%	600
	11th to 20th	Night	19% 10% 33% 33% 5%	600
	21st to end	Night	17% 8% 35% 33% 7%	660
April	1st to 10th	Night	16% 9% 34% 33% 8%	600
	11th to 20th	Night	15% 8% 33% 35% 9% 1	593
	21st to end	Night	14% 6% 33% 35% 12%	600
May	1st to 10th	Night	16% 4 20% 49% 12%	600
	11th to 20th	Night	16% 6% 21% 34% 22% 1	591
	21st to end	Night	10% 3 14% 44% 25% 4	650
June	1st to 10th	Night	5% 2 10% 41% 37% 4	600
	11th to 20th	Night	5% 1 7% 43% 41% 3	600
	21st to end	Night	3 1 6% 36% 47% 6%	600
July	1st to 10th	Night	6% 1 6% 33% 48% 7%	585
	11th to 20th	Night	3 2 5% 31% 50% 8%	582
	21st to end	Night	4 1 4 31% 49% 10%	657
August	1st to 10th	Night	4 1 5% 35% 50% 5%	597
	11th to 20th	Night	8% 2 4 35% 45% 6%	594
	21st to end	Night	7% 1 5% 28% 51% 7%	660
September	1st to 10th	Night	9% 1 4 35% 46% 4	579
	11th to 20th	Night	11% 2 7% 33% 44% 3	570
	21st to end	Night	10% 2 11% 35% 38% 4	651
October	1st to 10th	Night	8% 2 12% 37% 37% 3	760
	11th to 20th	Night	11% 4 23% 42% 19% 1	760
	21st to end	Night	18% 6% 22% 36% 16% 2	836
November	1st to 10th	Night	14% 5% 20% 45% 16% 1	780
	11th to 20th	Night	13% 8% 27% 40% 12%	800
	21st to end	Night	15% 10% 27% 35% 12%	873
December	1st to 10th	Night	21% 6% 28% 38% 7%	1000
	11th to 20th	Night	22% 8% 25% 38% 7%	1000
	21st to end	Night	20% 12% 28% 35% 5%	1100

Page generated at 2025-09-01 00:51:09. Version ac07

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