Texas Yard Canon Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Texas Yard Canon Observatory clear sky chart from 2005-11-06 to 2024-11-11.

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% 9% 3 8% 5% 4 5% 4 6% 7% 37%	101417
	Night	14% 10% 3 7% 5% 4 4 3 5% 6% 38%	97811
Transparency	Day	43% 7% 13% 23% 13% 1	104959
	Night	44% 7% 11% 22% 14% 2	102396
Seeing	Day	16% 12% 29% 26% 12% 5%	15903
	Night	17% 10% 31% 29% 12% 1	25749

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	10% 16% 8% 12% 5% 4 5% 3 4 5% 28%	2527
	11th to 20th	Day	11% 14% 6% 16% 5% 4 5% 8% 7% 6% 21%	2530
	21st to end	Day	16% 19% 9% 11% 5% 4 3 2 3 5% 21%	2819
February	1st to 10th	Day	11% 14% 5% 10% 5% 5% 5% 4 4 7% 30%	1710
	11th to 20th	Day	13% 12% 3 7% 5% 5% 5% 4 5% 5% 36%	1845
	21st to end	Day	11% 15% 4 12% 5% 5% 4 4 5% 5% 30%	1570
March	1st to 10th	Day	13% 9% 3 7% 4 4 5% 3 5% 6% 41%	3120
	11th to 20th	Day	11% 7% 3 8% 5% 4 5% 4 5% 6% 43%	3273
	21st to end	Day	21% 12% 4 10% 5% 4 4 3 4 6% 27%	4165
April	1st to 10th	Day	17% 14% 3 7% 6% 5% 5% 4 6% 5% 30%	2280
	11th to 20th	Day	15% 11% 4 7% 5% 4 4 4 6% 7% 34%	2254
	21st to end	Day	18% 10% 3 7% 4 4 4 4 5% 6% 34%	2395
May	1st to 10th	Day	15% 8% 2 7% 5% 4 4 3 7% 6% 37%	4082
	11th to 20th	Day	13% 7% 3 6% 4 4 4 3 6% 7% 43%	4399
	21st to end	Day	12% 7% 2 7% 4 4 5% 5% 6% 9% 39%	4824
June	1st to 10th	Day	10% 6% 2 6% 5% 5% 5% 4 5% 9% 44%	2660
	11th to 20th	Day	11% 6% 2 5% 5% 4 4 4 7% 9% 44%	2660
	21st to end	Day	12% 6% 2 6% 5% 5% 4 5% 7% 8% 40%	2660
July	1st to 10th	Day	11% 8% 2 7% 5% 5% 5% 5% 7% 9% 34%	4440
	11th to 20th	Day	5% 3 2 5% 4 5% 6% 5% 7% 9% 49%	4440
	21st to end	Day	7% 6% 3 7% 6% 5% 5% 5% 6% 9% 42%	4813
August	1st to 10th	Day	9% 6% 2 6% 5% 4 6% 5% 7% 10% 40%	4405
	11th to 20th	Day	10% 5% 2 6% 4 4 5% 4 7% 8% 44%	3773
	21st to end	Day	8% 6% 3 7% 4 4 5% 3 6% 9% 46%	4180
September	1st to 10th	Day	11% 6% 2 7% 4 4 4 4 6% 8% 44%	2280
	11th to 20th	Day	12% 5% 2 5% 3 3 4 3 6% 8% 49%	2173
	21st to end	Day	12% 6% 2 7% 4 4 4 4 7% 6% 43%	2090
October	1st to 10th	Day	14% 7% 2 6% 4 3 4 3 5% 6% 46%	2013
	11th to 20th	Day	19% 8% 3 8% 5% 4 5% 4 5% 7% 34%	1881
	21st to end	Day	18% 9% 3 8% 4 5% 4 2 5% 6% 38%	1881
November	1st to 10th	Day	11% 10% 3 6% 5% 3 4 3 5% 6% 43%	1762
	11th to 20th	Day	12% 11% 5% 9% 6% 5% 5% 4 5% 7% 32%	1710
	21st to end	Day	17% 11% 3 7% 4 3 4 2 4 6% 37%	1582
December	1st to 10th	Day	13% 11% 4 11% 6% 6% 5% 3 5% 6% 30%	1520
	11th to 20th	Day	13% 13% 4 10% 6% 5% 5% 4 6% 6% 28%	1918
	21st to end	Day	19% 21% 9% 12% 5% 4 4 3 4 3 16%	2783
January	1st to 10th	Night	13% 14% 8% 10% 5% 5% 4 2 4 5% 31%	4428
	11th to 20th	Night	12% 16% 6% 14% 7% 4 5% 5% 6% 5% 20%	4440
	21st to end	Night	17% 18% 8% 11% 5% 4 4 3 5% 5% 22%	4843
February	1st to 10th	Night	12% 14% 5% 10% 6% 4 4 3 4 6% 33%	2470
	11th to 20th	Night	12% 10% 3 7% 5% 5% 4 4 6% 5% 40%	2220
	21st to end	Night	17% 12% 3 7% 5% 4 4 4 5% 6% 35%	1884
March	1st to 10th	Night	17% 10% 3 6% 4 4 4 3 4 5% 41%	3733
	11th to 20th	Night	9% 7% 2 6% 4 4 5% 4 5% 9% 46%	3716
	21st to end	Night	21% 12% 5% 10% 5% 4 4 3 4 4 29%	3466
April	1st to 10th	Night	16% 10% 3 6% 5% 5% 5% 3 5% 7% 36%	1900
	11th to 20th	Night	19% 8% 3 7% 5% 4 4 4 4 5% 37%	1875
	21st to end	Night	18% 9% 3 5% 3 4 4 4 5% 6% 39%	1783
May	1st to 10th	Night	16% 8% 3 6% 4 4 4 4 6% 8% 37%	2796
	11th to 20th	Night	14% 6% 3 6% 4 4 4 4 6% 7% 41%	2506
	21st to end	Night	12% 9% 3 7% 4 4 4 3 5% 6% 43%	2743
June	1st to 10th	Night	9% 5% 2 6% 4 4 4 4 7% 8% 47%	1520
	11th to 20th	Night	11% 6% 2 6% 4 4 4 4 7% 8% 45%	1520
	21st to end	Night	9% 6% 2 6% 5% 4 4 4 6% 8% 46%	1520
July	1st to 10th	Night	13% 7% 3 7% 5% 5% 4 4 5% 7% 40%	2530
	11th to 20th	Night	5% 3 1 5% 4 3 4 4 7% 9% 56%	2530
	21st to end	Night	5% 4 2 6% 5% 5% 5% 3 8% 10% 47%	2750
August	1st to 10th	Night	9% 5% 2 5% 4 4 4 3 5% 8% 50%	2534
	11th to 20th	Night	9% 6% 2 6% 4 3 4 3 6% 8% 49%	3040
	21st to end	Night	8% 5% 2 5% 4 4 5% 3 6% 9% 50%	3476
September	1st to 10th	Night	8% 6% 2 6% 4 3 3 3 5% 6% 54%	1900
	11th to 20th	Night	11% 4 2 5% 3 3 4 3 5% 7% 53%	1987
	21st to end	Night	12% 6% 2 6% 4 5% 3 3 5% 6% 48%	2090
October	1st to 10th	Night	11% 6% 3 6% 4 4 4 3 5% 6% 50%	2165
	11th to 20th	Night	16% 7% 2 5% 4 4 4 2 4 6% 44%	2299
	21st to end	Night	19% 8% 3 6% 5% 3 4 3 5% 7% 36%	2717
November	1st to 10th	Night	13% 7% 2 6% 4 4 3 4 4 6% 47%	2536
	11th to 20th	Night	14% 10% 5% 8% 5% 5% 5% 3 6% 6% 35%	2477
	21st to end	Night	17% 10% 3 6% 5% 4 4 4 5% 6% 37%	2594
December	1st to 10th	Night	15% 12% 4 8% 5% 6% 4 5% 5% 6% 31%	2660
	11th to 20th	Night	15% 13% 4 10% 5% 5% 5% 4 5% 5% 29%	3279
	21st to end	Night	21% 18% 5% 10% 5% 5% 4 3 4 5% 19%	4884

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	59% 7% 12% 16% 6%	2528
	11th to 20th	Day	59% 8% 12% 15% 6%	2530
	21st to end	Day	66% 5% 7% 16% 5%	2819
February	1st to 10th	Day	53% 7% 12% 17% 10% 1	1710
	11th to 20th	Day	48% 6% 11% 23% 10% 2	1855
	21st to end	Day	55% 6% 10% 17% 10% 2	1570
March	1st to 10th	Day	43% 7% 10% 24% 12% 3	3120
	11th to 20th	Day	40% 7% 12% 27% 12% 1	3273
	21st to end	Day	58% 8% 13% 15% 5% 2	4165
April	1st to 10th	Day	55% 7% 11% 18% 10%	2280
	11th to 20th	Day	48% 7% 11% 19% 12% 3	2254
	21st to end	Day	48% 8% 12% 18% 12% 1	2395
May	1st to 10th	Day	42% 9% 13% 21% 14%	4120
	11th to 20th	Day	38% 9% 12% 28% 13%	4403
	21st to end	Day	37% 10% 14% 20% 16% 3	4837
June	1st to 10th	Day	35% 8% 14% 25% 17% 2	2660
	11th to 20th	Day	35% 7% 15% 24% 18% 2	2660
	21st to end	Day	38% 9% 14% 22% 15% 2	2660
July	1st to 10th	Day	43% 7% 14% 25% 9% 2	4371
	11th to 20th	Day	27% 9% 17% 29% 17% 1	4365
	21st to end	Day	36% 9% 15% 19% 19% 2	4662
August	1st to 10th	Day	36% 9% 14% 29% 11% 1	4390
	11th to 20th	Day	34% 9% 13% 31% 12% 1	3810
	21st to end	Day	35% 7% 13% 24% 20% 1	4179
September	1st to 10th	Day	36% 8% 13% 25% 16% 2	2280
	11th to 20th	Day	32% 5% 13% 31% 17% 2	2173
	21st to end	Day	38% 8% 12% 28% 14% 1	2090
October	1st to 10th	Day	24% 4 7% 40% 24% 1	3338
	11th to 20th	Day	34% 5% 11% 27% 22% 1	3109
	21st to end	Day	41% 5% 10% 28% 13% 3	3081
November	1st to 10th	Day	42% 6% 14% 23% 14% 1	1762
	11th to 20th	Day	50% 7% 13% 20% 9% 1	1710
	21st to end	Day	49% 5% 14% 25% 7%	1582
December	1st to 10th	Day	54% 7% 14% 16% 8% 1	1520
	11th to 20th	Day	53% 7% 15% 16% 7% 2	1915
	21st to end	Day	72% 6% 9% 9% 5%	2783
January	1st to 10th	Night	55% 7% 10% 18% 9% 1	4428
	11th to 20th	Night	63% 7% 11% 12% 7%	4440
	21st to end	Night	63% 7% 10% 13% 6% 1	4843
February	1st to 10th	Night	52% 6% 11% 17% 12% 2	2470
	11th to 20th	Night	44% 6% 12% 21% 15% 1	2221
	21st to end	Night	50% 5% 11% 19% 11% 4	1884
March	1st to 10th	Night	45% 7% 12% 24% 9% 3	3733
	11th to 20th	Night	33% 8% 13% 26% 17% 3	3716
	21st to end	Night	58% 7% 8% 16% 10% 1	3466
April	1st to 10th	Night	45% 9% 10% 20% 15% 1	1900
	11th to 20th	Night	49% 5% 7% 19% 17% 4	1875
	21st to end	Night	43% 9% 13% 19% 15% 2	1783
May	1st to 10th	Night	42% 8% 14% 18% 16% 2	2823
	11th to 20th	Night	38% 9% 14% 26% 12% 1	2507
	21st to end	Night	39% 9% 10% 18% 17% 7%	2751
June	1st to 10th	Night	32% 8% 14% 26% 18% 2	1520
	11th to 20th	Night	35% 6% 12% 23% 21% 2	1520
	21st to end	Night	35% 8% 16% 22% 17% 2	1520
July	1st to 10th	Night	42% 6% 15% 21% 12% 4	2490
	11th to 20th	Night	22% 8% 16% 35% 17% 2	2482
	21st to end	Night	28% 10% 15% 21% 22% 3	2662
August	1st to 10th	Night	31% 8% 15% 28% 18% 1	2525
	11th to 20th	Night	31% 8% 12% 33% 15% 1	3068
	21st to end	Night	29% 7% 13% 28% 20% 3	3476
September	1st to 10th	Night	30% 7% 12% 26% 23% 2	1900
	11th to 20th	Night	30% 6% 10% 33% 19% 2	1987
	21st to end	Night	37% 5% 10% 30% 17% 1	2090
October	1st to 10th	Night	24% 5% 7% 38% 25% 1	3607
	11th to 20th	Night	34% 6% 11% 25% 22% 2	3810
	21st to end	Night	41% 5% 9% 26% 17% 2	4467
November	1st to 10th	Night	38% 6% 10% 26% 17% 2	2536
	11th to 20th	Night	48% 6% 14% 19% 11% 1	2477
	21st to end	Night	47% 6% 15% 21% 10% 1	2594
December	1st to 10th	Night	53% 8% 10% 19% 9% 1	2660
	11th to 20th	Night	55% 7% 11% 17% 9% 1	3281
	21st to end	Night	66% 6% 10% 13% 5%	4884

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	16% 19% 34% 24% 6% 1	270
	11th to 20th	Day	20% 17% 38% 20% 4 1	270
	21st to end	Day	22% 15% 38% 20% 4 1	297
February	1st to 10th	Day	14% 21% 42% 17% 5% 1	270
	11th to 20th	Day	22% 23% 35% 16% 3	270
	21st to end	Day	21% 23% 41% 12% 3	225
March	1st to 10th	Day	17% 25% 41% 13% 3	270
	11th to 20th	Day	24% 21% 29% 20% 4 1	284
	21st to end	Day	26% 15% 29% 21% 6% 2	506
April	1st to 10th	Day	24% 15% 34% 22% 5%	460
	11th to 20th	Day	22% 22% 25% 20% 9% 2	452
	21st to end	Day	23% 13% 29% 22% 13% 1	460
May	1st to 10th	Day	21% 13% 32% 25% 8% 2	463
	11th to 20th	Day	21% 12% 30% 25% 9% 3	675
	21st to end	Day	17% 10% 29% 26% 13% 6%	734
June	1st to 10th	Day	9% 9% 32% 30% 14% 5%	680
	11th to 20th	Day	14% 8% 29% 31% 12% 5%	680
	21st to end	Day	15% 8% 31% 30% 12% 4	680
July	1st to 10th	Day	8% 4 23% 31% 25% 10%	671
	11th to 20th	Day	9% 6% 26% 34% 18% 8%	668
	21st to end	Day	5% 4 29% 37% 16% 9%	739
August	1st to 10th	Day	9% 3 22% 37% 19% 11%	671
	11th to 20th	Day	11% 5% 17% 31% 24% 12%	479
	21st to end	Day	9% 6% 21% 31% 25% 8%	539
September	1st to 10th	Day	14% 7% 23% 28% 20% 8%	490
	11th to 20th	Day	11% 3 21% 30% 24% 10%	490
	21st to end	Day	17% 11% 24% 26% 16% 7%	490
October	1st to 10th	Day	17% 11% 27% 26% 14% 5%	413
	11th to 20th	Day	22% 19% 29% 21% 8%	300
	21st to end	Day	27% 16% 35% 17% 4 1	330
November	1st to 10th	Day	18% 17% 35% 21% 8% 1	300
	11th to 20th	Day	20% 20% 35% 18% 7%	270
	21st to end	Day	23% 15% 40% 18% 4	270
December	1st to 10th	Day	20% 19% 40% 14% 6% 1	270
	11th to 20th	Day	18% 20% 36% 18% 8% 1	270
	21st to end	Day	25% 23% 36% 14% 1	297
January	1st to 10th	Night	19% 17% 36% 22% 6%	950
	11th to 20th	Night	21% 15% 36% 22% 6% 1	950
	21st to end	Night	19% 11% 39% 25% 6%	1045
February	1st to 10th	Night	21% 13% 36% 25% 5%	950
	11th to 20th	Night	19% 17% 35% 25% 5%	745
	21st to end	Night	24% 14% 39% 19% 4	628
March	1st to 10th	Night	21% 13% 35% 23% 8% 1	760
	11th to 20th	Night	16% 14% 36% 26% 7%	729
	21st to end	Night	22% 9% 32% 29% 7% 1	627
April	1st to 10th	Night	21% 12% 36% 24% 6%	570
	11th to 20th	Night	22% 13% 32% 25% 7% 1	563
	21st to end	Night	22% 10% 31% 26% 10% 1	570
May	1st to 10th	Night	19% 9% 34% 32% 6% 1	570
	11th to 20th	Night	19% 5% 30% 34% 11%	561
	21st to end	Night	13% 6% 27% 34% 18% 1	617
June	1st to 10th	Night	10% 5% 27% 42% 16% 1	570
	11th to 20th	Night	13% 4 32% 36% 14% 1	570
	21st to end	Night	10% 5% 27% 42% 16% 1	570
July	1st to 10th	Night	8% 2 18% 39% 30% 3	555
	11th to 20th	Night	8% 2 22% 40% 24% 3	552
	21st to end	Night	5% 3 18% 47% 25% 2	624
August	1st to 10th	Night	8% 2 15% 48% 25% 2	567
	11th to 20th	Night	9% 3 15% 39% 28% 5%	564
	21st to end	Night	10% 3 18% 39% 28% 3	627
September	1st to 10th	Night	8% 4 22% 37% 24% 5%	570
	11th to 20th	Night	12% 5% 22% 30% 28% 4	657
	21st to end	Night	14% 7% 26% 28% 21% 3	760
October	1st to 10th	Night	14% 8% 29% 31% 17% 2	760
	11th to 20th	Night	21% 11% 32% 27% 9%	760
	21st to end	Night	24% 11% 32% 25% 9%	836
November	1st to 10th	Night	17% 12% 36% 24% 10% 1	780
	11th to 20th	Night	20% 16% 35% 23% 6%	763
	21st to end	Night	22% 14% 36% 22% 6%	884
December	1st to 10th	Night	21% 15% 38% 21% 5%	950
	11th to 20th	Night	23% 13% 36% 22% 5%	950
	21st to end	Night	29% 14% 35% 19% 3	1045

Page generated at 2024-11-08 05:44:49. Version ac07

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