Corpus Christi
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Corpus Christi clear sky chart from 2005-11-06 to 2024-11-06.

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	11% 5% 2 6% 4 4 5% 4 6% 9% 44%	100959
	Night	13% 6% 2 5% 4 4 4 3 5% 8% 46%	98211
Transparency	Day	20% 48% 9% 12% 7% 3	104764
	Night	20% 47% 9% 12% 8% 4	102533
Seeing	Day	12% 3 13% 30% 33% 9%	14545
	Night	14% 4 15% 33% 29% 5%	24468

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	16% 8% 3 7% 4 4 3 3 5% 6% 42%	2847
	11th to 20th	Day	14% 5% 2 4 3 3 3 4 5% 7% 50%	2850
	21st to end	Day	21% 7% 2 6% 3 3 4 4 6% 7% 35%	3400
February	1st to 10th	Day	20% 7% 3 6% 3 4 3 4 6% 5% 39%	1900
	11th to 20th	Day	19% 8% 3 6% 4 4 3 2 4 6% 42%	1849
	21st to end	Day	17% 8% 2 6% 4 4 3 3 5% 5% 43%	1627
March	1st to 10th	Day	20% 9% 3 6% 5% 4 5% 3 7% 8% 31%	3436
	11th to 20th	Day	26% 9% 4 8% 4 4 4 3 4 6% 28%	3480
	21st to end	Day	10% 5% 2 6% 5% 4 5% 4 6% 7% 48%	3814
April	1st to 10th	Day	13% 7% 2 6% 4 4 5% 3 7% 8% 41%	2090
	11th to 20th	Day	16% 7% 2 7% 4 4 3 3 6% 7% 41%	2066
	21st to end	Day	11% 7% 2 6% 5% 4 4 3 7% 8% 42%	2242
May	1st to 10th	Day	17% 7% 3 7% 5% 4 5% 4 7% 10% 31%	4082
	11th to 20th	Day	10% 6% 2 7% 5% 5% 5% 5% 6% 8% 42%	4082
	21st to end	Day	6% 4 2 4 4 4 5% 4 8% 11% 48%	4477
June	1st to 10th	Day	4 2 1 4 3 4 4 4 8% 12% 55%	2470
	11th to 20th	Day	4 3 2 5% 5% 4 4 4 7% 13% 49%	2470
	21st to end	Day	6% 5% 2 4 4 5% 6% 6% 9% 13% 41%	2470
July	1st to 10th	Day	6% 5% 2 6% 4 5% 5% 4 7% 10% 46%	4120
	11th to 20th	Day	5% 6% 3 9% 6% 7% 7% 5% 8% 12% 33%	4120
	21st to end	Day	9% 6% 2 6% 5% 4 5% 5% 7% 12% 39%	4465
August	1st to 10th	Day	1 1 2 2 2 2 3 5% 8% 74%	4076
	11th to 20th	Day	3 2 1 3 3 3 4 5% 9% 14% 52%	3726
	21st to end	Day	5% 3 2 5% 4 6% 6% 6% 8% 14% 42%	3838
September	1st to 10th	Day	9% 5% 2 7% 5% 5% 6% 6% 8% 11% 36%	2090
	11th to 20th	Day	10% 6% 3 7% 5% 5% 5% 4 7% 9% 40%	2090
	21st to end	Day	8% 4 1 5% 3 4 5% 4 7% 10% 47%	2090
October	1st to 10th	Day	6% 4 1 5% 4 4 5% 4 5% 8% 53%	2090
	11th to 20th	Day	10% 5% 1 5% 4 4 4 4 5% 8% 51%	1940
	21st to end	Day	8% 5% 1 5% 3 3 3 3 4 8% 57%	2090
November	1st to 10th	Day	9% 5% 2 6% 4 5% 5% 4 6% 9% 45%	1908
	11th to 20th	Day	14% 7% 2 6% 4 3 4 3 4 7% 46%	1900
	21st to end	Day	16% 6% 2 7% 4 4 5% 4 5% 6% 41%	1758
December	1st to 10th	Day	18% 7% 2 6% 3 4 4 3 5% 5% 43%	1710
	11th to 20th	Day	14% 8% 3 7% 5% 5% 4 4 5% 6% 39%	2161
	21st to end	Day	17% 6% 2 6% 4 4 4 3 5% 7% 42%	3135
January	1st to 10th	Night	19% 7% 2 6% 4 3 3 2 4 6% 42%	4108
	11th to 20th	Night	15% 6% 2 5% 3 2 3 2 4 7% 52%	4120
	21st to end	Night	24% 7% 3 6% 4 4 3 3 6% 6% 35%	4294
February	1st to 10th	Night	19% 8% 2 5% 3 5% 5% 3 5% 6% 41%	2280
	11th to 20th	Night	20% 7% 2 4 3 3 3 3 5% 6% 44%	2218
	21st to end	Night	19% 9% 2 6% 4 3 3 2 4 6% 42%	1825
March	1st to 10th	Night	25% 9% 2 5% 3 3 4 3 5% 8% 32%	3419
	11th to 20th	Night	26% 10% 3 9% 5% 4 4 4 4 5% 26%	3480
	21st to end	Night	15% 6% 2 4 3 2 3 1 3 6% 54%	3817
April	1st to 10th	Night	15% 8% 3 7% 5% 4 4 3 6% 8% 38%	2090
	11th to 20th	Night	19% 6% 2 6% 4 4 3 3 4 8% 41%	2063
	21st to end	Night	16% 8% 2 7% 5% 4 3 3 5% 7% 39%	1932
May	1st to 10th	Night	27% 7% 2 5% 4 3 4 3 5% 8% 33%	2823
	11th to 20th	Night	18% 6% 3 6% 4 5% 3 4 7% 7% 38%	2823
	21st to end	Night	11% 6% 2 7% 4 5% 5% 4 6% 9% 40%	3090
June	1st to 10th	Night	4 3 2 4 3 3 4 4 9% 10% 54%	1710
	11th to 20th	Night	4 4 1 5% 4 4 5% 5% 7% 12% 50%	1710
	21st to end	Night	5% 4 2 5% 5% 5% 5% 5% 8% 11% 48%	1710
July	1st to 10th	Night	5% 3 1 5% 3 4 4 4 6% 10% 54%	2850
	11th to 20th	Night	3 4 2 6% 5% 6% 5% 5% 9% 14% 40%	2850
	21st to end	Night	8% 5% 2 6% 4 4 4 4 7% 12% 44%	3098
August	1st to 10th	Night	1 1 2 1 2 2 3 7% 81%	2858
	11th to 20th	Night	2 2 1 3 3 3 4 4 7% 14% 57%	3113
	21st to end	Night	2 3 1 4 3 2 5% 4 6% 13% 59%	3817
September	1st to 10th	Night	6% 6% 2 7% 4 4 5% 5% 7% 10% 44%	2090
	11th to 20th	Night	8% 6% 2 6% 4 4 4 3 7% 10% 45%	2090
	21st to end	Night	6% 4 2 5% 4 4 4 3 5% 9% 54%	2090
October	1st to 10th	Night	4 3 1 3 3 4 4 4 5% 8% 61%	2090
	11th to 20th	Night	9% 4 1 4 3 3 3 2 5% 8% 58%	2218
	21st to end	Night	9% 3 2 4 3 3 2 2 4 7% 62%	2508
November	1st to 10th	Night	10% 5% 2 4 3 3 4 3 6% 7% 54%	2292
	11th to 20th	Night	15% 5% 2 6% 4 3 3 3 3 6% 51%	2280
	21st to end	Night	16% 6% 2 6% 4 4 4 3 5% 5% 44%	2417
December	1st to 10th	Night	17% 7% 2 6% 4 3 3 3 4 6% 45%	2470
	11th to 20th	Night	17% 9% 3 7% 5% 3 4 3 5% 7% 38%	3036
	21st to end	Night	14% 8% 3 6% 4 4 5% 3 6% 6% 42%	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	28% 40% 4 11% 10% 7%	2848
	11th to 20th	Day	19% 42% 7% 15% 10% 7%	2850
	21st to end	Day	30% 40% 3 10% 12% 4	3400
February	1st to 10th	Day	19% 65% 3 3 5% 5%	1900
	11th to 20th	Day	14% 65% 4 8% 7% 2	1859
	21st to end	Day	18% 66% 2 5% 5% 3	1627
March	1st to 10th	Day	39% 44% 5% 8% 3 1	3436
	11th to 20th	Day	40% 42% 6% 7% 4 1	3480
	21st to end	Day	19% 41% 9% 13% 11% 7%	3814
April	1st to 10th	Day	15% 65% 4 4 6% 5%	2090
	11th to 20th	Day	16% 66% 5% 5% 4 3	2066
	21st to end	Day	13% 66% 4 9% 5% 2	2242
May	1st to 10th	Day	32% 43% 12% 7% 4 2	4120
	11th to 20th	Day	26% 43% 8% 9% 9% 4	4086
	21st to end	Day	17% 46% 9% 26% 3	4489
June	1st to 10th	Day	7% 66% 8% 14% 5%	2470
	11th to 20th	Day	11% 68% 6% 10% 4 1	2470
	21st to end	Day	10% 67% 8% 12% 2	2470
July	1st to 10th	Day	15% 39% 23% 21% 2	4056
	11th to 20th	Day	30% 42% 17% 8% 3	4051
	21st to end	Day	26% 39% 18% 16% 1	4325
August	1st to 10th	Day	4 38% 13% 33% 12%	4062
	11th to 20th	Day	10% 42% 26% 21% 2	3762
	21st to end	Day	17% 42% 16% 19% 5% 1	3837
September	1st to 10th	Day	13% 66% 6% 8% 6% 1	2090
	11th to 20th	Day	14% 62% 7% 10% 6% 1	2090
	21st to end	Day	13% 63% 8% 11% 3 2	2090
October	1st to 10th	Day	12% 37% 5% 6% 19% 20%	3480
	11th to 20th	Day	18% 39% 7% 8% 21% 7%	3206
	21st to end	Day	16% 38% 5% 17% 20% 5%	3428
November	1st to 10th	Day	19% 61% 6% 8% 4 2	1908
	11th to 20th	Day	21% 61% 4 6% 3 4	1900
	21st to end	Day	21% 60% 3 7% 7% 2	1758
December	1st to 10th	Day	19% 60% 2 8% 8% 2	1710
	11th to 20th	Day	21% 48% 5% 6% 11% 8%	2159
	21st to end	Day	30% 38% 4 13% 10% 5%	3135
January	1st to 10th	Night	32% 39% 4 7% 6% 12%	4108
	11th to 20th	Night	20% 39% 3 16% 14% 8%	4120
	21st to end	Night	32% 39% 4 8% 12% 5%	4294
February	1st to 10th	Night	19% 65% 3 3 5% 5%	2280
	11th to 20th	Night	14% 64% 4 8% 6% 4	2218
	21st to end	Night	16% 65% 3 7% 5% 4	1825
March	1st to 10th	Night	38% 42% 8% 8% 4	3419
	11th to 20th	Night	44% 40% 7% 4 3 2	3480
	21st to end	Night	17% 40% 7% 13% 18% 5%	3817
April	1st to 10th	Night	16% 65% 3 5% 6% 4	2090
	11th to 20th	Night	17% 66% 5% 4 4 4	2063
	21st to end	Night	16% 65% 5% 7% 5% 2	1932
May	1st to 10th	Night	32% 40% 10% 10% 5% 3	2850
	11th to 20th	Night	29% 41% 9% 12% 7% 3	2824
	21st to end	Night	24% 41% 9% 23% 2	3099
June	1st to 10th	Night	7% 65% 8% 14% 6%	1710
	11th to 20th	Night	12% 67% 3 10% 7%	1710
	21st to end	Night	12% 65% 8% 13% 2	1710
July	1st to 10th	Night	11% 38% 24% 24% 2	2805
	11th to 20th	Night	24% 41% 21% 11% 2	2796
	21st to end	Night	24% 39% 21% 15% 2	2999
August	1st to 10th	Night	3 37% 11% 38% 11%	2848
	11th to 20th	Night	10% 39% 27% 22% 1	3143
	21st to end	Night	8% 41% 21% 23% 6% 1	3817
September	1st to 10th	Night	11% 62% 12% 7% 7% 2	2090
	11th to 20th	Night	12% 61% 8% 12% 6% 1	2090
	21st to end	Night	13% 63% 7% 12% 3 2	2090
October	1st to 10th	Night	10% 37% 6% 10% 15% 23%	3480
	11th to 20th	Night	12% 38% 7% 10% 23% 10%	3678
	21st to end	Night	13% 38% 5% 16% 23% 5%	4120
November	1st to 10th	Night	18% 60% 7% 8% 5% 3	2292
	11th to 20th	Night	22% 60% 5% 6% 4 3	2280
	21st to end	Night	21% 60% 4 7% 6% 2	2417
December	1st to 10th	Night	19% 59% 4 7% 8% 3	2470
	11th to 20th	Night	21% 50% 3 8% 8% 10%	3037
	21st to end	Night	31% 37% 7% 8% 10% 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	19% 8% 24% 35% 13%	270
	11th to 20th	Day	19% 8% 20% 39% 12% 2	270
	21st to end	Day	21% 5% 29% 33% 11%	297
February	1st to 10th	Day	26% 6% 23% 33% 11% 1	270
	11th to 20th	Day	25% 7% 24% 34% 10%	270
	21st to end	Day	23% 5% 34% 33% 4	225
March	1st to 10th	Day	22% 6% 24% 38% 10%	270
	11th to 20th	Day	25% 6% 28% 34% 7%	270
	21st to end	Day	16% 7% 32% 39% 6%	297
April	1st to 10th	Day	15% 6% 33% 37% 9% 1	270
	11th to 20th	Day	19% 9% 27% 31% 13% 1	264
	21st to end	Day	15% 6% 28% 38% 13%	422
May	1st to 10th	Day	13% 4 27% 45% 11%	653
	11th to 20th	Day	10% 5% 18% 48% 17% 1	675
	21st to end	Day	7% 3 14% 46% 28% 1	734
June	1st to 10th	Day	5% 1 5% 36% 45% 8%	680
	11th to 20th	Day	6% 1 4 37% 46% 6%	680
	21st to end	Day	7% 1 4 26% 49% 14%	680
July	1st to 10th	Day	6% 1 3 25% 49% 15%	671
	11th to 20th	Day	4 1 1 18% 58% 19%	668
	21st to end	Day	5% 2 1 17% 56% 19%	739
August	1st to 10th	Day	1 1 1 15% 58% 26%	661
	11th to 20th	Day	3 1 1 14% 63% 18%	477
	21st to end	Day	6% 1 2 11% 46% 35%	340
September	1st to 10th	Day	10% 1 3 15% 49% 21%	300
	11th to 20th	Day	8% 1 2 12% 48% 29%	300
	21st to end	Day	7% 2 4 13% 49% 25%	300
October	1st to 10th	Day	9% 4 3 24% 48% 13%	300
	11th to 20th	Day	13% 2 4 28% 40% 12%	300
	21st to end	Day	13% 2 16% 34% 29% 5%	330
November	1st to 10th	Day	13% 4 11% 31% 38% 3	285
	11th to 20th	Day	22% 4 11% 32% 26% 4	270
	21st to end	Day	28% 6% 18% 31% 14% 3	270
December	1st to 10th	Day	20% 6% 16% 33% 22% 3	270
	11th to 20th	Day	23% 7% 21% 33% 15% 1	270
	21st to end	Day	22% 8% 20% 34% 14% 2	297
January	1st to 10th	Night	21% 7% 23% 34% 14% 1	950
	11th to 20th	Night	21% 6% 23% 37% 13%	950
	21st to end	Night	21% 5% 24% 37% 12%	898
February	1st to 10th	Night	24% 6% 23% 38% 9%	760
	11th to 20th	Night	24% 7% 23% 36% 11%	744
	21st to end	Night	25% 6% 27% 32% 9%	569
March	1st to 10th	Night	19% 6% 23% 38% 14%	570
	11th to 20th	Night	21% 6% 22% 41% 10%	570
	21st to end	Night	15% 5% 24% 44% 11% 1	627
April	1st to 10th	Night	18% 4 27% 41% 10%	570
	11th to 20th	Night	22% 6% 22% 36% 14%	563
	21st to end	Night	18% 4 22% 41% 13%	570
May	1st to 10th	Night	16% 3 22% 45% 14%	570
	11th to 20th	Night	13% 2 18% 48% 17% 2	561
	21st to end	Night	8% 2 14% 44% 31% 1	617
June	1st to 10th	Night	5% 1 4 36% 50% 4	570
	11th to 20th	Night	5% 1 4 44% 45% 2	570
	21st to end	Night	5% 1 5% 29% 48% 11%	570
July	1st to 10th	Night	6% 1 2 28% 50% 12%	555
	11th to 20th	Night	3 1 1 18% 59% 17%	552
	21st to end	Night	5% 1 1 18% 63% 12%	624
August	1st to 10th	Night	1 1 13% 67% 17%	567
	11th to 20th	Night	4 1 1 11% 70% 14%	564
	21st to end	Night	4 1 2 14% 54% 26%	627
September	1st to 10th	Night	6% 2 3 18% 53% 18%	570
	11th to 20th	Night	10% 2 2 14% 52% 20%	570
	21st to end	Night	8% 1 3 21% 54% 13%	570
October	1st to 10th	Night	4 1 5% 24% 54% 11%	570
	11th to 20th	Night	11% 2 8% 34% 41% 5%	698
	21st to end	Night	10% 3 12% 38% 33% 4	836
November	1st to 10th	Night	10% 3 10% 35% 37% 5%	764
	11th to 20th	Night	17% 3 16% 34% 27% 3	760
	21st to end	Night	21% 6% 18% 34% 19% 3	897
December	1st to 10th	Night	20% 5% 18% 31% 22% 4	950
	11th to 20th	Night	22% 6% 20% 35% 16% 1	950
	21st to end	Night	21% 7% 24% 33% 14% 1	1045

Page generated at 2024-11-03 12:19:04. Version ac07

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