Mission Tejas State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Mission Tejas State Park clear sky chart from 2005-11-06 to 2024-11-05.

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% 6% 2 6% 4 4 4 4 5% 7% 44%	101133
	Night	13% 6% 2 5% 3 3 4 3 5% 7% 49%	97999
Transparency	Day	38% 4 11% 21% 19% 7%	104808
	Night	34% 4 11% 20% 21% 10%	102451
Seeing	Day	14% 8% 23% 27% 22% 6%	15030
	Night	15% 8% 25% 32% 17% 2	24852

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% 10% 3 5% 3 3 3 2 4 6% 46%	2847
	11th to 20th	Day	20% 6% 1 4 2 2 3 2 4 6% 51%	2850
	21st to end	Day	25% 8% 2 5% 3 2 2 2 3 5% 43%	3135
February	1st to 10th	Day	22% 9% 3 7% 4 3 3 2 2 5% 40%	1733
	11th to 20th	Day	22% 8% 2 6% 4 3 4 2 3 5% 40%	1849
	21st to end	Day	21% 7% 3 5% 4 3 3 2 4 4 43%	1727
March	1st to 10th	Day	19% 13% 3 8% 4 4 3 3 5% 5% 33%	3436
	11th to 20th	Day	22% 7% 2 6% 4 3 5% 3 5% 7% 35%	3480
	21st to end	Day	18% 9% 3 6% 4 4 4 3 5% 6% 38%	3814
April	1st to 10th	Day	14% 7% 3 7% 5% 4 4 4 5% 6% 42%	2090
	11th to 20th	Day	16% 7% 3 6% 4 5% 5% 4 6% 7% 39%	2244
	21st to end	Day	12% 6% 2 5% 4 4 5% 4 5% 6% 46%	2280
May	1st to 10th	Day	20% 8% 3 9% 5% 4 5% 4 6% 8% 29%	3944
	11th to 20th	Day	15% 6% 2 7% 4 4 4 3 5% 6% 44%	4082
	21st to end	Day	12% 7% 2 7% 5% 5% 6% 5% 7% 10% 34%	4477
June	1st to 10th	Day	6% 5% 2 6% 5% 6% 6% 5% 8% 10% 40%	2470
	11th to 20th	Day	5% 4 2 5% 6% 6% 6% 5% 7% 11% 43%	2470
	21st to end	Day	6% 5% 2 6% 6% 5% 6% 6% 8% 11% 40%	2470
July	1st to 10th	Day	9% 5% 2 6% 6% 5% 6% 5% 8% 11% 37%	4120
	11th to 20th	Day	5% 5% 2 6% 5% 5% 5% 5% 7% 10% 44%	4120
	21st to end	Day	14% 8% 3 8% 5% 5% 5% 4 6% 8% 32%	4465
August	1st to 10th	Day	3 1 1 2 2 2 3 3 5% 9% 69%	4104
	11th to 20th	Day	3 2 1 3 3 4 4 3 7% 10% 58%	3923
	21st to end	Day	7% 4 2 6% 5% 5% 6% 5% 7% 11% 43%	4180
September	1st to 10th	Day	7% 6% 2 7% 5% 6% 6% 4 6% 7% 45%	2115
	11th to 20th	Day	12% 6% 2 6% 5% 5% 5% 4 6% 6% 43%	2090
	21st to end	Day	7% 3 2 5% 4 4 5% 3 6% 8% 53%	2090
October	1st to 10th	Day	7% 3 1 4 3 4 4 3 4 6% 62%	1952
	11th to 20th	Day	13% 5% 2 3 2 3 4 3 4 5% 57%	1900
	21st to end	Day	14% 5% 2 4 3 3 3 2 3 5% 56%	2090
November	1st to 10th	Day	13% 7% 2 5% 3 3 4 4 5% 6% 48%	1898
	11th to 20th	Day	13% 6% 2 5% 4 3 4 3 4 6% 52%	1900
	21st to end	Day	18% 7% 2 7% 4 3 3 3 5% 4 44%	1782
December	1st to 10th	Day	17% 6% 2 5% 4 3 3 3 5% 6% 45%	1710
	11th to 20th	Day	18% 8% 2 5% 4 4 3 3 4 5% 43%	2161
	21st to end	Day	16% 9% 3 8% 4 3 4 3 4 5% 42%	3135
January	1st to 10th	Night	16% 7% 1 5% 3 2 3 3 4 6% 52%	4108
	11th to 20th	Night	19% 6% 1 4 2 2 3 2 3 4 54%	4120
	21st to end	Night	23% 10% 2 5% 3 2 3 2 3 5% 42%	4532
February	1st to 10th	Night	18% 9% 3 5% 3 3 4 3 4 5% 45%	2464
	11th to 20th	Night	19% 9% 2 5% 3 3 4 2 4 4 45%	2218
	21st to end	Night	20% 7% 2 5% 3 3 3 3 4 5% 45%	1727
March	1st to 10th	Night	22% 10% 3 5% 5% 3 3 3 4 5% 36%	3419
	11th to 20th	Night	21% 7% 2 6% 4 4 3 4 6% 7% 37%	3480
	21st to end	Night	16% 6% 2 6% 4 4 4 3 5% 5% 45%	3817
April	1st to 10th	Night	12% 5% 1 6% 4 4 4 3 5% 6% 48%	2090
	11th to 20th	Night	14% 6% 2 6% 3 3 4 3 5% 7% 46%	1883
	21st to end	Night	13% 5% 2 5% 3 3 4 3 4 6% 52%	1900
May	1st to 10th	Night	17% 9% 2 6% 4 3 4 3 6% 8% 38%	2953
	11th to 20th	Night	14% 6% 2 7% 4 4 4 3 5% 6% 46%	2823
	21st to end	Night	12% 5% 2 5% 4 4 5% 3 7% 9% 43%	3090
June	1st to 10th	Night	5% 3 1 5% 4 3 4 4 6% 11% 55%	1710
	11th to 20th	Night	3 3 1 3 2 3 3 3 6% 9% 63%	1710
	21st to end	Night	6% 4 1 4 4 4 4 4 7% 11% 51%	1710
July	1st to 10th	Night	7% 4 2 6% 4 4 5% 4 7% 11% 46%	2850
	11th to 20th	Night	3 3 1 5% 4 4 4 4 6% 11% 55%	2850
	21st to end	Night	11% 8% 3 6% 4 4 4 4 6% 9% 40%	3098
August	1st to 10th	Night	2 1 1 1 2 2 3 4 9% 75%	2836
	11th to 20th	Night	3 2 1 3 3 3 4 4 6% 12% 59%	2909
	21st to end	Night	4 3 1 4 5% 5% 5% 5% 9% 10% 48%	3476
September	1st to 10th	Night	7% 5% 2 5% 4 4 5% 3 5% 9% 51%	2060
	11th to 20th	Night	9% 5% 2 6% 4 4 4 3 6% 7% 50%	2090
	21st to end	Night	7% 4 1 4 3 3 3 3 5% 7% 59%	2090
October	1st to 10th	Night	5% 3 1 4 3 2 3 3 5% 6% 65%	2206
	11th to 20th	Night	12% 4 1 3 3 2 3 3 4 5% 60%	2280
	21st to end	Night	15% 4 1 3 3 2 2 2 3 4 60%	2508
November	1st to 10th	Night	14% 4 2 4 3 3 3 3 4 6% 55%	2280
	11th to 20th	Night	10% 6% 2 4 3 3 3 4 4 6% 54%	2280
	21st to end	Night	16% 7% 2 5% 3 3 4 3 5% 5% 47%	2394
December	1st to 10th	Night	16% 7% 1 4 3 3 4 4 4 6% 47%	2470
	11th to 20th	Night	16% 8% 2 6% 4 3 4 2 3 6% 46%	3036
	21st to end	Night	16% 7% 2 5% 3 3 3 3 3 5% 49%	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	41% 3 4 20% 26% 5%	2848
	11th to 20th	Day	38% 2 5% 24% 27% 5%	2850
	21st to end	Day	47% 1 4 19% 19% 10%	3135
February	1st to 10th	Day	50% 2 4 14% 19% 10%	1733
	11th to 20th	Day	50% 2 5% 15% 19% 9%	1859
	21st to end	Day	46% 2 7% 14% 18% 13%	1727
March	1st to 10th	Day	55% 4 7% 13% 17% 5%	3436
	11th to 20th	Day	49% 3 9% 18% 16% 4	3480
	21st to end	Day	48% 3 9% 17% 20% 3	3814
April	1st to 10th	Day	43% 4 9% 19% 17% 8%	2090
	11th to 20th	Day	44% 4 10% 15% 18% 8%	2244
	21st to end	Day	38% 5% 9% 20% 24% 5%	2280
May	1st to 10th	Day	52% 5% 12% 18% 10% 4	3979
	11th to 20th	Day	41% 3 10% 19% 25% 1	4086
	21st to end	Day	45% 5% 16% 21% 12% 1	4489
June	1st to 10th	Day	38% 6% 15% 25% 15% 1	2470
	11th to 20th	Day	33% 6% 14% 28% 16% 3	2470
	21st to end	Day	37% 9% 14% 25% 14% 2	2470
July	1st to 10th	Day	37% 10% 24% 23% 6%	4056
	11th to 20th	Day	34% 6% 16% 30% 13%	4051
	21st to end	Day	47% 7% 16% 22% 8%	4325
August	1st to 10th	Day	15% 4 13% 35% 31% 2	4090
	11th to 20th	Day	21% 5% 21% 42% 10% 1	3962
	21st to end	Day	34% 9% 19% 23% 13% 2	4179
September	1st to 10th	Day	37% 6% 13% 19% 17% 9%	2115
	11th to 20th	Day	40% 6% 12% 17% 18% 7%	2090
	21st to end	Day	30% 4 9% 22% 21% 13%	2090
October	1st to 10th	Day	15% 3 6% 13% 23% 41%	3238
	11th to 20th	Day	19% 2 4 23% 30% 22%	3140
	21st to end	Day	26% 3 4 18% 37% 12%	3428
November	1st to 10th	Day	37% 4 8% 20% 23% 10%	1898
	11th to 20th	Day	36% 3 6% 20% 24% 11%	1900
	21st to end	Day	45% 3 6% 18% 20% 9%	1782
December	1st to 10th	Day	42% 3 9% 18% 19% 9%	1710
	11th to 20th	Day	45% 2 6% 16% 22% 9%	2159
	21st to end	Day	47% 2 5% 14% 24% 9%	3135
January	1st to 10th	Night	37% 3 5% 18% 28% 9%	4108
	11th to 20th	Night	37% 2 5% 16% 29% 10%	4120
	21st to end	Night	48% 2 4 16% 20% 10%	4532
February	1st to 10th	Night	44% 3 5% 15% 18% 15%	2464
	11th to 20th	Night	44% 3 6% 16% 20% 11%	2218
	21st to end	Night	44% 3 8% 13% 17% 16%	1727
March	1st to 10th	Night	52% 3 7% 15% 17% 7%	3419
	11th to 20th	Night	48% 4 10% 14% 18% 6%	3480
	21st to end	Night	42% 3 10% 15% 23% 7%	3817
April	1st to 10th	Night	38% 4 9% 20% 16% 12%	2090
	11th to 20th	Night	38% 3 11% 20% 16% 12%	1883
	21st to end	Night	35% 4 10% 19% 25% 7%	1900
May	1st to 10th	Night	45% 4 12% 21% 14% 4	2983
	11th to 20th	Night	41% 3 11% 18% 23% 3	2824
	21st to end	Night	37% 4 18% 26% 12% 2	3099
June	1st to 10th	Night	26% 6% 17% 31% 19% 1	1710
	11th to 20th	Night	19% 5% 19% 33% 20% 5%	1710
	21st to end	Night	28% 6% 15% 29% 20% 2	1710
July	1st to 10th	Night	31% 7% 28% 28% 6%	2805
	11th to 20th	Night	23% 8% 22% 32% 14%	2796
	21st to end	Night	40% 7% 20% 25% 8%	2999
August	1st to 10th	Night	9% 3 16% 35% 33% 4	2826
	11th to 20th	Night	18% 5% 21% 44% 10% 2	2936
	21st to end	Night	29% 9% 20% 24% 16% 2	3476
September	1st to 10th	Night	32% 5% 15% 22% 17% 10%	2060
	11th to 20th	Night	34% 6% 14% 19% 18% 9%	2090
	21st to end	Night	26% 3 11% 21% 26% 12%	2090
October	1st to 10th	Night	13% 3 5% 15% 19% 44%	3687
	11th to 20th	Night	17% 2 3 19% 33% 26%	3779
	21st to end	Night	24% 3 4 16% 36% 17%	4120
November	1st to 10th	Night	32% 4 9% 19% 25% 11%	2280
	11th to 20th	Night	33% 3 7% 19% 24% 13%	2280
	21st to end	Night	40% 3 8% 16% 22% 11%	2394
December	1st to 10th	Night	39% 3 9% 19% 20% 9%	2470
	11th to 20th	Night	43% 2 6% 14% 22% 13%	3037
	21st to end	Night	40% 2 6% 14% 29% 9%	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	26% 15% 39% 16% 3 1	270
	11th to 20th	Day	28% 15% 34% 16% 6% 1	270
	21st to end	Day	28% 17% 37% 14% 4	297
February	1st to 10th	Day	29% 20% 32% 16% 3	270
	11th to 20th	Day	37% 21% 29% 13% 1	270
	21st to end	Day	29% 26% 36% 5% 3	225
March	1st to 10th	Day	29% 17% 34% 17% 3	270
	11th to 20th	Day	23% 27% 33% 13% 3	270
	21st to end	Day	24% 16% 40% 16% 3	297
April	1st to 10th	Day	24% 15% 45% 15% 1	270
	11th to 20th	Day	24% 18% 26% 23% 9% 1	442
	21st to end	Day	14% 13% 40% 27% 6% 1	460
May	1st to 10th	Day	18% 11% 37% 26% 8% 1	564
	11th to 20th	Day	15% 8% 27% 33% 15% 2	675
	21st to end	Day	12% 9% 29% 31% 16% 4	734
June	1st to 10th	Day	7% 3 16% 38% 27% 8%	680
	11th to 20th	Day	6% 2 19% 42% 25% 6%	680
	21st to end	Day	8% 3 14% 33% 30% 12%	680
July	1st to 10th	Day	8% 1 13% 30% 37% 12%	671
	11th to 20th	Day	3 1 8% 33% 43% 11%	668
	21st to end	Day	6% 2 9% 33% 40% 10%	739
August	1st to 10th	Day	4 1 5% 31% 46% 13%	676
	11th to 20th	Day	6% 1 4 30% 46% 14%	599
	21st to end	Day	10% 2 9% 17% 42% 19%	539
September	1st to 10th	Day	6% 1 8% 30% 39% 16%	325
	11th to 20th	Day	9% 1 12% 30% 34% 13%	300
	21st to end	Day	10% 2 13% 32% 29% 14%	300
October	1st to 10th	Day	6% 3 20% 40% 24% 7%	300
	11th to 20th	Day	10% 6% 32% 34% 14% 5%	300
	21st to end	Day	23% 10% 26% 22% 15% 3	330
November	1st to 10th	Day	17% 7% 30% 30% 13% 3	282
	11th to 20th	Day	18% 13% 33% 26% 7% 2	270
	21st to end	Day	24% 16% 30% 22% 6% 2	270
December	1st to 10th	Day	20% 10% 34% 22% 11% 3	270
	11th to 20th	Day	29% 15% 32% 19% 5%	270
	21st to end	Day	25% 14% 40% 15% 5% 1	297
January	1st to 10th	Night	22% 12% 33% 26% 7%	950
	11th to 20th	Night	25% 14% 29% 25% 7%	950
	21st to end	Night	23% 12% 34% 28% 3	1045
February	1st to 10th	Night	24% 14% 35% 24% 3	944
	11th to 20th	Night	28% 14% 32% 23% 3	744
	21st to end	Night	27% 15% 36% 20% 2	471
March	1st to 10th	Night	23% 13% 34% 23% 7%	570
	11th to 20th	Night	20% 15% 35% 25% 6%	570
	21st to end	Night	16% 11% 41% 26% 5%	627
April	1st to 10th	Night	13% 14% 40% 26% 7%	570
	11th to 20th	Night	17% 14% 36% 23% 10%	563
	21st to end	Night	14% 12% 40% 25% 9% 1	570
May	1st to 10th	Night	11% 10% 42% 28% 9% 1	570
	11th to 20th	Night	13% 6% 33% 34% 12% 2	561
	21st to end	Night	9% 4 30% 38% 16% 3	617
June	1st to 10th	Night	6% 2 16% 42% 32% 4	570
	11th to 20th	Night	3 2 19% 50% 24% 2	570
	21st to end	Night	7% 1 12% 44% 29% 6%	570
July	1st to 10th	Night	5% 1 10% 43% 35% 6%	555
	11th to 20th	Night	3 2 9% 44% 36% 6%	552
	21st to end	Night	6% 2 7% 41% 39% 5%	624
August	1st to 10th	Night	3 1 6% 45% 39% 7%	567
	11th to 20th	Night	6% 7% 43% 38% 6%	564
	21st to end	Night	7% 1 7% 36% 42% 8%	627
September	1st to 10th	Night	8% 1 10% 37% 38% 6%	570
	11th to 20th	Night	11% 2 11% 29% 41% 6%	570
	21st to end	Night	9% 2 9% 38% 37% 5%	570
October	1st to 10th	Night	6% 2 15% 40% 31% 5%	686
	11th to 20th	Night	13% 6% 22% 39% 18% 2	760
	21st to end	Night	18% 8% 25% 30% 18% 2	836
November	1st to 10th	Night	15% 4 26% 35% 19% 2	760
	11th to 20th	Night	14% 10% 26% 38% 12%	760
	21st to end	Night	20% 11% 29% 27% 13% 1	874
December	1st to 10th	Night	21% 9% 32% 29% 9% 1	950
	11th to 20th	Night	25% 11% 29% 30% 5%	950
	21st to end	Night	22% 14% 29% 28% 7%	1045

Page generated at 2024-11-03 01:11:08. Version ac07

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