Martin Dies, Jr. State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Martin Dies, Jr. State Park clear sky chart from 2005-11-06 to 2024-04-10.

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	14% 6% 3 6% 6% 3 5% 5% 6% 7% 40%	83686
	Night	14% 6% 2 4 4 3 4 4 5% 7% 46%	85148
Transparency	Day	43% 6% 10% 18% 17% 6%	83411
	Night	38% 6% 11% 19% 19% 8%	84943
Seeing	Day	15% 8% 21% 25% 22% 9%	14096
	Night	16% 7% 23% 32% 19% 3	24093

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	21% 8% 3 5% 4 2 4 4 5% 6% 40%	2847
	11th to 20th	Day	20% 6% 2 4 4 2 2 2 3 5% 50%	2850
	21st to end	Day	24% 8% 3 5% 4 2 3 3 4 7% 37%	3135
February	1st to 10th	Day	20% 8% 4 6% 6% 4 5% 3 3 4 37%	1710
	11th to 20th	Day	23% 8% 4 5% 4 2 3 3 3 4 41%	1892
	21st to end	Day	20% 8% 3 6% 5% 3 4 3 4 6% 37%	1727
March	1st to 10th	Day	20% 12% 4 8% 6% 3 4 4 4 6% 29%	3436
	11th to 20th	Day	19% 7% 3 7% 7% 4 5% 5% 6% 7% 31%	3480
	21st to end	Day	18% 9% 3 6% 5% 2 4 4 4 5% 40%	3814
April	1st to 10th	Day	14% 7% 3 7% 6% 4 5% 5% 5% 5% 39%	2130
	11th to 20th	Day	16% 7% 3 6% 6% 3 5% 5% 6% 6% 38%	2134
	21st to end	Day	12% 5% 3 6% 6% 4 5% 4 6% 6% 43%	2160
May	1st to 10th	Day	12% 6% 3 6% 6% 4 5% 5% 6% 8% 38%	2160
	11th to 20th	Day	10% 6% 3 6% 6% 3 5% 4 6% 7% 42%	2251
	21st to end	Day	10% 5% 3 6% 7% 5% 8% 7% 8% 10% 32%	2531
June	1st to 10th	Day	8% 5% 2 6% 7% 5% 7% 7% 7% 10% 36%	2340
	11th to 20th	Day	6% 3 2 5% 7% 5% 8% 6% 8% 11% 38%	2340
	21st to end	Day	8% 6% 3 6% 7% 5% 8% 7% 9% 11% 30%	2340
July	1st to 10th	Day	9% 4 3 7% 8% 5% 7% 7% 9% 10% 30%	2340
	11th to 20th	Day	7% 5% 2 6% 6% 5% 8% 7% 8% 10% 35%	2340
	21st to end	Day	7% 4 3 6% 8% 4 7% 8% 8% 10% 36%	2546
August	1st to 10th	Day	3 3 3 4 6% 5% 7% 7% 8% 12% 42%	2328
	11th to 20th	Day	6% 4 1 6% 5% 5% 8% 7% 8% 11% 40%	2147
	21st to end	Day	9% 5% 2 6% 7% 5% 8% 7% 7% 9% 36%	2376
September	1st to 10th	Day	8% 5% 3 6% 6% 4 7% 6% 7% 8% 41%	2122
	11th to 20th	Day	14% 5% 3 6% 7% 4 5% 5% 6% 7% 38%	1980
	21st to end	Day	10% 3 2 5% 5% 3 5% 5% 5% 7% 48%	1973
October	1st to 10th	Day	8% 3 2 5% 5% 3 4 4 4 6% 57%	1800
	11th to 20th	Day	12% 4 2 4 5% 2 4 4 4 7% 52%	1800
	21st to end	Day	15% 5% 2 4 4 2 3 3 4 5% 53%	1980
November	1st to 10th	Day	11% 5% 2 5% 5% 3 5% 4 5% 7% 50%	1858
	11th to 20th	Day	11% 7% 2 6% 5% 3 4 4 4 6% 50%	1900
	21st to end	Day	17% 7% 3 6% 5% 3 4 4 4 4 44%	1900
December	1st to 10th	Day	17% 8% 3 5% 5% 2 4 4 5% 5% 42%	1723
	11th to 20th	Day	16% 9% 3 6% 6% 3 4 5% 4 4 40%	2161
	21st to end	Day	17% 8% 3 5% 6% 3 3 4 5% 6% 42%	3135
January	1st to 10th	Night	17% 8% 2 4 3 2 3 3 4 6% 47%	4108
	11th to 20th	Night	20% 8% 3 4 3 2 3 2 3 4 50%	4120
	21st to end	Night	25% 11% 2 4 3 2 2 3 3 6% 38%	4532
February	1st to 10th	Night	18% 9% 3 5% 5% 3 3 4 4 6% 40%	2470
	11th to 20th	Night	22% 9% 3 4 4 2 3 3 3 5% 42%	2187
	21st to end	Night	20% 8% 3 6% 4 3 4 3 4 4 40%	1727
March	1st to 10th	Night	24% 12% 3 6% 5% 3 4 3 4 6% 31%	3419
	11th to 20th	Night	22% 8% 4 6% 5% 3 4 4 4 6% 34%	3480
	21st to end	Night	14% 7% 3 5% 5% 3 4 5% 4 6% 43%	3817
April	1st to 10th	Night	14% 5% 2 6% 4 3 5% 4 5% 8% 42%	2038
	11th to 20th	Night	16% 6% 2 4 5% 3 4 4 5% 7% 45%	1775
	21st to end	Night	12% 5% 2 5% 5% 3 4 4 5% 8% 47%	1800
May	1st to 10th	Night	13% 6% 3 4 5% 3 5% 4 6% 9% 42%	1800
	11th to 20th	Night	12% 4 3 5% 5% 2 4 4 5% 8% 49%	1639
	21st to end	Night	8% 5% 1 4 5% 3 5% 5% 7% 10% 48%	1745
June	1st to 10th	Night	5% 4 2 5% 5% 3 4 6% 6% 10% 50%	1620
	11th to 20th	Night	4 3 1 3 3 2 5% 5% 7% 10% 58%	1620
	21st to end	Night	7% 5% 2 4 5% 3 5% 6% 9% 11% 45%	1620
July	1st to 10th	Night	6% 4 3 4 6% 3 5% 7% 8% 13% 42%	1620
	11th to 20th	Night	5% 2 2 3 4 2 5% 5% 8% 11% 52%	1620
	21st to end	Night	3 2 3 4 5% 3 4 6% 8% 13% 48%	1772
August	1st to 10th	Night	3 2 1 3 3 2 3 4 7% 13% 60%	1611
	11th to 20th	Night	3 3 2 4 4 3 5% 5% 9% 12% 49%	1751
	21st to end	Night	9% 4 2 5% 5% 3 5% 5% 8% 11% 43%	1980
September	1st to 10th	Night	5% 4 2 5% 4 3 5% 5% 7% 11% 48%	1833
	11th to 20th	Night	12% 5% 3 5% 5% 3 4 5% 7% 7% 44%	1980
	21st to end	Night	9% 5% 3 4 4 2 3 4 5% 6% 55%	1980
October	1st to 10th	Night	6% 3 2 3 4 2 4 5% 4 6% 61%	2146
	11th to 20th	Night	11% 3 2 3 3 2 3 4 5% 6% 56%	2160
	21st to end	Night	12% 5% 2 3 4 2 3 3 4 5% 58%	2376
November	1st to 10th	Night	11% 5% 2 4 4 3 4 4 4 6% 55%	2220
	11th to 20th	Night	11% 5% 2 5% 4 3 4 3 5% 6% 52%	2280
	21st to end	Night	16% 7% 2 5% 4 3 3 4 4 6% 46%	2280
December	1st to 10th	Night	21% 8% 2 5% 4 2 4 3 4 5% 42%	2454
	11th to 20th	Night	17% 9% 2 5% 5% 3 4 3 4 5% 44%	3036
	21st to end	Night	18% 7% 2 4 4 3 4 4 4 6% 44%	4532

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	45% 4 5% 17% 22% 8%	2848
	11th to 20th	Day	40% 3 5% 17% 30% 6%	2850
	21st to end	Day	48% 3 4 16% 18% 10%	3135
February	1st to 10th	Day	51% 4 5% 12% 18% 10%	1710
	11th to 20th	Day	49% 3 5% 15% 17% 10%	1902
	21st to end	Day	49% 4 7% 13% 16% 10%	1727
March	1st to 10th	Day	56% 5% 8% 12% 15% 5%	3436
	11th to 20th	Day	51% 6% 7% 17% 14% 5%	3480
	21st to end	Day	47% 5% 7% 15% 22% 4	3814
April	1st to 10th	Day	47% 5% 7% 15% 18% 8%	2130
	11th to 20th	Day	46% 5% 9% 14% 16% 10%	2134
	21st to end	Day	40% 6% 8% 18% 23% 5%	2160
May	1st to 10th	Day	43% 6% 9% 19% 16% 6%	2160
	11th to 20th	Day	40% 7% 10% 23% 17% 2	2255
	21st to end	Day	44% 9% 14% 20% 12% 1	2531
June	1st to 10th	Day	41% 9% 14% 20% 14% 1	2340
	11th to 20th	Day	37% 9% 15% 23% 14% 2	2340
	21st to end	Day	44% 10% 16% 19% 10% 1	2340
July	1st to 10th	Day	44% 11% 18% 20% 6%	2276
	11th to 20th	Day	39% 10% 19% 23% 8%	2271
	21st to end	Day	37% 12% 20% 22% 8% 1	2405
August	1st to 10th	Day	32% 9% 21% 27% 10% 1	2314
	11th to 20th	Day	34% 13% 19% 24% 9% 1	2147
	21st to end	Day	42% 11% 17% 19% 9% 2	2376
September	1st to 10th	Day	38% 8% 14% 18% 16% 5%	2122
	11th to 20th	Day	44% 8% 12% 16% 14% 6%	1980
	21st to end	Day	34% 6% 11% 21% 19% 10%	1973
October	1st to 10th	Day	29% 5% 10% 22% 23% 12%	1800
	11th to 20th	Day	33% 4 6% 18% 25% 14%	1800
	21st to end	Day	35% 4 5% 14% 27% 16%	1980
November	1st to 10th	Day	35% 6% 9% 18% 21% 11%	1858
	11th to 20th	Day	38% 4 6% 16% 25% 12%	1900
	21st to end	Day	44% 4 5% 18% 20% 9%	1900
December	1st to 10th	Day	45% 5% 8% 17% 17% 8%	1723
	11th to 20th	Day	48% 3 6% 14% 20% 9%	2159
	21st to end	Day	43% 4 7% 14% 25% 8%	3135
January	1st to 10th	Night	39% 3 6% 19% 24% 8%	4108
	11th to 20th	Night	41% 2 5% 17% 28% 8%	4120
	21st to end	Night	50% 3 4 17% 16% 10%	4532
February	1st to 10th	Night	46% 3 7% 15% 17% 12%	2470
	11th to 20th	Night	47% 3 6% 15% 20% 10%	2187
	21st to end	Night	48% 5% 6% 12% 16% 13%	1727
March	1st to 10th	Night	55% 4 7% 13% 14% 6%	3419
	11th to 20th	Night	52% 6% 9% 14% 14% 5%	3480
	21st to end	Night	42% 6% 9% 14% 24% 6%	3817
April	1st to 10th	Night	41% 7% 8% 18% 16% 10%	2038
	11th to 20th	Night	38% 6% 10% 18% 15% 12%	1775
	21st to end	Night	37% 6% 9% 18% 24% 6%	1800
May	1st to 10th	Night	39% 7% 12% 17% 18% 7%	1800
	11th to 20th	Night	34% 5% 11% 25% 21% 4	1640
	21st to end	Night	30% 7% 19% 28% 15% 1	1746
June	1st to 10th	Night	28% 10% 18% 28% 16% 1	1620
	11th to 20th	Night	21% 8% 18% 34% 16% 2	1620
	21st to end	Night	30% 10% 22% 26% 11% 1	1620
July	1st to 10th	Night	31% 13% 25% 25% 7%	1575
	11th to 20th	Night	22% 11% 33% 25% 9%	1566
	21st to end	Night	25% 12% 31% 23% 8% 1	1673
August	1st to 10th	Night	16% 9% 30% 34% 10% 1	1601
	11th to 20th	Night	24% 11% 28% 26% 10% 1	1751
	21st to end	Night	33% 11% 23% 21% 10% 3	1980
September	1st to 10th	Night	29% 9% 20% 20% 15% 6%	1833
	11th to 20th	Night	39% 7% 14% 18% 16% 6%	1980
	21st to end	Night	30% 5% 12% 22% 19% 12%	1980
October	1st to 10th	Night	24% 6% 9% 26% 20% 15%	2146
	11th to 20th	Night	29% 4 8% 19% 24% 15%	2160
	21st to end	Night	31% 3 7% 15% 25% 19%	2376
November	1st to 10th	Night	31% 4 11% 18% 23% 12%	2220
	11th to 20th	Night	33% 4 9% 18% 25% 11%	2280
	21st to end	Night	40% 4 8% 16% 21% 10%	2280
December	1st to 10th	Night	45% 5% 7% 18% 16% 9%	2454
	11th to 20th	Night	44% 4 5% 12% 22% 14%	3037
	21st to end	Night	42% 5% 7% 14% 26% 7%	4532

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% 19% 38% 13% 5% 1	270
	11th to 20th	Day	27% 15% 31% 21% 5% 1	270
	21st to end	Day	27% 21% 32% 17% 3	297
February	1st to 10th	Day	26% 19% 35% 16% 3 1	270
	11th to 20th	Day	35% 15% 32% 16% 2	270
	21st to end	Day	28% 29% 33% 9% 1	225
March	1st to 10th	Day	28% 19% 31% 17% 6%	270
	11th to 20th	Day	21% 24% 36% 15% 4 1	270
	21st to end	Day	24% 14% 42% 16% 3 1	297
April	1st to 10th	Day	16% 17% 42% 19% 4 1	318
	11th to 20th	Day	25% 15% 25% 24% 9% 1	412
	21st to end	Day	16% 13% 33% 26% 9% 2	420
May	1st to 10th	Day	18% 9% 33% 26% 12% 1	423
	11th to 20th	Day	13% 6% 25% 35% 18% 3	574
	21st to end	Day	9% 5% 26% 34% 20% 6%	679
June	1st to 10th	Day	10% 2 16% 31% 29% 12%	630
	11th to 20th	Day	6% 2 17% 39% 28% 9%	630
	21st to end	Day	10% 2 13% 26% 33% 15%	630
July	1st to 10th	Day	7% 2 8% 28% 38% 17%	621
	11th to 20th	Day	6% 1 6% 25% 43% 19%	618
	21st to end	Day	6% 6% 27% 41% 20%	684
August	1st to 10th	Day	5% 1 5% 23% 43% 23%	626
	11th to 20th	Day	7% 2 1 17% 49% 25%	461
	21st to end	Day	12% 2 7% 16% 36% 27%	495
September	1st to 10th	Day	7% 1 7% 22% 41% 23%	412
	11th to 20th	Day	9% 2 13% 31% 30% 15%	270
	21st to end	Day	14% 3 10% 30% 31% 12%	270
October	1st to 10th	Day	8% 1 20% 36% 27% 7%	270
	11th to 20th	Day	10% 7% 23% 34% 18% 8%	270
	21st to end	Day	24% 8% 27% 24% 13% 4	297
November	1st to 10th	Day	13% 7% 29% 29% 20% 3	270
	11th to 20th	Day	16% 13% 33% 30% 8% 1	270
	21st to end	Day	25% 14% 32% 20% 6% 3	270
December	1st to 10th	Day	20% 11% 34% 24% 6% 4	270
	11th to 20th	Day	25% 12% 35% 22% 5%	270
	21st to end	Day	27% 16% 34% 18% 4 2	297
January	1st to 10th	Night	23% 13% 30% 28% 6%	950
	11th to 20th	Night	26% 12% 28% 27% 7%	950
	21st to end	Night	24% 12% 31% 29% 4	1045
February	1st to 10th	Night	25% 13% 32% 26% 4	950
	11th to 20th	Night	29% 13% 32% 23% 4	712
	21st to end	Night	27% 18% 31% 23% 1	471
March	1st to 10th	Night	27% 10% 31% 26% 5%	570
	11th to 20th	Night	21% 12% 34% 28% 5% 1	570
	21st to end	Night	18% 10% 38% 26% 9%	627
April	1st to 10th	Night	18% 9% 39% 27% 6%	570
	11th to 20th	Night	19% 9% 32% 28% 11%	533
	21st to end	Night	14% 8% 38% 29% 10% 1	540
May	1st to 10th	Night	18% 7% 32% 32% 10% 1	540
	11th to 20th	Night	14% 3 28% 38% 15% 1	531
	21st to end	Night	8% 4 24% 37% 23% 3	584
June	1st to 10th	Night	6% 1 11% 40% 35% 6%	540
	11th to 20th	Night	4 1 18% 45% 27% 5%	540
	21st to end	Night	9% 1 11% 34% 38% 7%	540
July	1st to 10th	Night	5% 1 6% 40% 38% 10%	525
	11th to 20th	Night	5% 1 7% 37% 43% 8%	522
	21st to end	Night	3 1 7% 36% 47% 6%	591
August	1st to 10th	Night	3 1 5% 39% 44% 8%	537
	11th to 20th	Night	4 1 4 38% 43% 10%	534
	21st to end	Night	9% 2 5% 29% 44% 11%	594
September	1st to 10th	Night	6% 1 6% 30% 45% 12%	540
	11th to 20th	Night	13% 1 9% 28% 41% 8%	540
	21st to end	Night	12% 3 10% 32% 34% 9%	540
October	1st to 10th	Night	6% 2 13% 37% 37% 5%	706
	11th to 20th	Night	13% 4 21% 39% 21% 3	720
	21st to end	Night	14% 8% 25% 31% 20% 2	792
November	1st to 10th	Night	12% 6% 24% 36% 21% 2	740
	11th to 20th	Night	14% 9% 24% 38% 13%	760
	21st to end	Night	19% 10% 30% 29% 12% 1	760
December	1st to 10th	Night	26% 9% 25% 29% 11% 1	934
	11th to 20th	Night	25% 9% 30% 29% 6%	950
	21st to end	Night	24% 10% 31% 28% 6%	1045

Page generated at 2024-04-07 08:28:15. Version ac07

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