Tyler
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Tyler clear sky chart from 2005-11-06 to 2024-09-14.

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 6% 7% 45%	100632
	Night	12% 6% 2 5% 3 3 3 3 5% 7% 51%	97359
Transparency	Day	38% 5% 11% 23% 19% 5%	100445
	Night	33% 4 11% 22% 22% 8%	97217
Seeing	Day	13% 7% 20% 28% 24% 9%	14957
	Night	13% 7% 26% 33% 19% 2	24746

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	15% 9% 3 7% 3 3 3 2 4 5% 47%	2847
	11th to 20th	Day	17% 5% 2 5% 3 2 3 3 4 5% 51%	2850
	21st to end	Day	24% 10% 3 6% 3 2 2 2 3 3 44%	3135
February	1st to 10th	Day	21% 9% 3 7% 3 3 3 3 3 5% 40%	1714
	11th to 20th	Day	19% 9% 2 6% 4 4 2 3 3 4 42%	1849
	21st to end	Day	22% 8% 2 5% 3 3 3 2 3 4 45%	1707
March	1st to 10th	Day	16% 11% 3 7% 4 4 3 3 5% 7% 37%	3436
	11th to 20th	Day	18% 8% 2 6% 5% 4 4 4 5% 7% 37%	3480
	21st to end	Day	16% 9% 3 7% 5% 3 4 3 6% 7% 38%	3814
April	1st to 10th	Day	13% 8% 2 5% 5% 3 4 4 4 6% 44%	2090
	11th to 20th	Day	15% 8% 2 6% 5% 4 4 4 6% 7% 40%	2252
	21st to end	Day	10% 6% 2 6% 5% 4 5% 4 6% 9% 43%	2280
May	1st to 10th	Day	20% 9% 3 8% 4 4 4 3 6% 6% 33%	4009
	11th to 20th	Day	15% 6% 2 7% 4 3 4 4 5% 6% 45%	4082
	21st to end	Day	13% 7% 3 7% 5% 5% 5% 5% 6% 8% 36%	4477
June	1st to 10th	Day	6% 5% 2 6% 5% 6% 5% 4 7% 10% 44%	2470
	11th to 20th	Day	4 4 1 5% 5% 5% 5% 5% 8% 10% 48%	2470
	21st to end	Day	5% 3 2 5% 5% 5% 5% 5% 8% 10% 47%	2470
July	1st to 10th	Day	7% 5% 2 6% 5% 5% 6% 6% 8% 11% 38%	4120
	11th to 20th	Day	4 3 1 4 4 4 5% 5% 7% 10% 52%	4120
	21st to end	Day	10% 9% 3 8% 5% 5% 6% 4 7% 8% 34%	4465
August	1st to 10th	Day	2 1 1 2 2 3 3 3 5% 8% 69%	4104
	11th to 20th	Day	3 3 1 3 3 3 4 5% 7% 11% 56%	3959
	21st to end	Day	4 5% 2 6% 5% 6% 7% 6% 8% 9% 41%	4180
September	1st to 10th	Day	8% 6% 3 5% 4 5% 4 3 6% 7% 49%	2126
	11th to 20th	Day	11% 6% 2 6% 5% 4 5% 4 6% 8% 43%	2013
	21st to end	Day	8% 3 2 4 4 4 4 3 5% 8% 56%	1980
October	1st to 10th	Day	7% 3 2 4 3 4 4 3 5% 6% 60%	1850
	11th to 20th	Day	13% 4 2 4 3 3 3 3 4 5% 55%	1800
	21st to end	Day	15% 5% 2 4 3 2 3 2 3 3 58%	1980
November	1st to 10th	Day	11% 6% 2 5% 3 3 3 3 5% 6% 53%	1858
	11th to 20th	Day	9% 6% 2 5% 5% 3 3 3 5% 5% 54%	1900
	21st to end	Day	17% 8% 3 6% 3 3 3 2 4 4 46%	1739
December	1st to 10th	Day	14% 8% 2 5% 3 2 2 4 5% 6% 48%	1710
	11th to 20th	Day	16% 8% 2 6% 5% 3 4 3 5% 7% 42%	2161
	21st to end	Day	16% 10% 3 8% 4 3 4 2 3 5% 43%	3135
January	1st to 10th	Night	15% 7% 2 5% 4 3 3 2 4 5% 50%	4108
	11th to 20th	Night	16% 7% 1 4 2 2 2 2 3 5% 56%	4120
	21st to end	Night	23% 9% 2 5% 3 3 3 2 3 4 44%	4532
February	1st to 10th	Night	17% 8% 2 5% 3 3 3 2 4 6% 46%	2470
	11th to 20th	Night	18% 8% 3 6% 3 3 3 2 3 5% 46%	2231
	21st to end	Night	18% 7% 1 5% 3 3 3 3 4 5% 47%	1746
March	1st to 10th	Night	20% 10% 2 6% 4 4 3 3 5% 6% 37%	3419
	11th to 20th	Night	15% 9% 3 7% 4 4 3 3 5% 6% 40%	3480
	21st to end	Night	14% 6% 3 6% 4 4 4 3 5% 6% 45%	3817
April	1st to 10th	Night	11% 4 2 5% 3 4 4 4 5% 8% 50%	2090
	11th to 20th	Night	11% 7% 1 5% 4 4 4 4 6% 7% 47%	1875
	21st to end	Night	11% 5% 2 4 4 3 3 3 6% 7% 53%	1900
May	1st to 10th	Night	15% 9% 3 7% 4 3 4 3 5% 8% 37%	2889
	11th to 20th	Night	11% 7% 3 8% 4 3 3 3 5% 8% 46%	2823
	21st to end	Night	11% 5% 2 5% 4 4 4 4 7% 8% 45%	3090
June	1st to 10th	Night	5% 3 2 4 3 3 4 4 9% 9% 55%	1710
	11th to 20th	Night	2 3 1 3 3 3 4 3 7% 8% 63%	1710
	21st to end	Night	4 4 2 4 4 3 4 4 6% 8% 57%	1710
July	1st to 10th	Night	6% 4 1 5% 3 3 5% 4 7% 13% 49%	2850
	11th to 20th	Night	2 3 1 4 3 3 3 3 7% 12% 60%	2850
	21st to end	Night	8% 7% 3 7% 5% 5% 4 5% 6% 10% 41%	3098
August	1st to 10th	Night	2 1 2 1 2 3 2 5% 8% 74%	2836
	11th to 20th	Night	3 2 1 3 2 2 4 3 7% 12% 61%	2875
	21st to end	Night	3 3 1 4 3 4 4 5% 8% 10% 55%	3476
September	1st to 10th	Night	8% 4 2 5% 3 4 4 3 6% 7% 54%	2048
	11th to 20th	Night	11% 4 2 5% 3 4 4 3 4 8% 53%	2024
	21st to end	Night	6% 3 1 4 2 3 3 3 5% 8% 61%	1980
October	1st to 10th	Night	5% 3 1 4 3 3 4 3 4 7% 63%	2092
	11th to 20th	Night	11% 5% 1 3 2 2 3 2 3 5% 62%	2160
	21st to end	Night	15% 5% 2 3 3 2 2 2 3 4 59%	2376
November	1st to 10th	Night	10% 5% 1 4 3 3 3 2 4 6% 60%	2220
	11th to 20th	Night	8% 5% 2 5% 4 4 3 3 5% 6% 55%	2280
	21st to end	Night	14% 7% 3 4 3 3 3 3 5% 5% 49%	2436
December	1st to 10th	Night	13% 7% 2 5% 3 3 4 3 5% 6% 48%	2470
	11th to 20th	Night	14% 8% 3 6% 4 3 3 3 4 5% 48%	3036
	21st to end	Night	15% 8% 2 5% 4 3 3 2 3 4 50%	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 19% 27% 5%	2848
	11th to 20th	Day	36% 4 7% 23% 26% 4	2850
	21st to end	Day	48% 1 4 16% 22% 10%	3135
February	1st to 10th	Day	48% 3 5% 17% 18% 9%	1714
	11th to 20th	Day	47% 3 5% 17% 19% 8%	1859
	21st to end	Day	43% 3 7% 14% 22% 11%	1707
March	1st to 10th	Day	48% 4 6% 15% 21% 6%	3436
	11th to 20th	Day	47% 3 7% 21% 17% 4	3480
	21st to end	Day	46% 4 9% 18% 20% 3	3814
April	1st to 10th	Day	40% 4 9% 22% 17% 9%	2090
	11th to 20th	Day	43% 5% 10% 16% 20% 7%	2252
	21st to end	Day	37% 5% 9% 22% 23% 4	2280
May	1st to 10th	Day	52% 4 11% 20% 10% 3	4046
	11th to 20th	Day	40% 3 10% 23% 23% 1	4086
	21st to end	Day	46% 4 14% 22% 11% 3	4489
June	1st to 10th	Day	32% 6% 16% 29% 14% 1	2470
	11th to 20th	Day	29% 6% 15% 30% 16% 4	2470
	21st to end	Day	29% 9% 12% 31% 17% 2	2470
July	1st to 10th	Day	35% 8% 24% 25% 8%	4056
	11th to 20th	Day	25% 7% 17% 36% 15% 1	4051
	21st to end	Day	45% 7% 14% 24% 10%	4325
August	1st to 10th	Day	13% 4 14% 34% 31% 4	4090
	11th to 20th	Day	20% 5% 17% 44% 13% 1	3998
	21st to end	Day	33% 9% 17% 25% 14% 1	4179
September	1st to 10th	Day	33% 5% 12% 22% 18% 10%	2126
	11th to 20th	Day	37% 8% 12% 17% 18% 8%	2013
	21st to end	Day	27% 4 9% 23% 25% 11%	1980
October	1st to 10th	Day	25% 4 11% 22% 22% 16%	1850
	11th to 20th	Day	32% 3 6% 17% 26% 16%	1800
	21st to end	Day	34% 3 4 17% 27% 15%	1980
November	1st to 10th	Day	33% 4 9% 20% 26% 9%	1858
	11th to 20th	Day	33% 2 7% 20% 27% 11%	1900
	21st to end	Day	43% 3 5% 17% 24% 8%	1739
December	1st to 10th	Day	38% 3 10% 20% 21% 8%	1710
	11th to 20th	Day	43% 2 6% 16% 23% 9%	2159
	21st to end	Day	46% 2 4 18% 23% 7%	3135
January	1st to 10th	Night	37% 3 5% 16% 32% 8%	4108
	11th to 20th	Night	34% 2 7% 18% 28% 12%	4120
	21st to end	Night	46% 2 5% 15% 22% 9%	4532
February	1st to 10th	Night	40% 3 6% 18% 19% 13%	2470
	11th to 20th	Night	43% 3 5% 17% 23% 10%	2231
	21st to end	Night	41% 3 8% 14% 20% 14%	1746
March	1st to 10th	Night	49% 3 6% 14% 17% 10%	3419
	11th to 20th	Night	45% 3 10% 16% 20% 6%	3480
	21st to end	Night	40% 3 9% 19% 24% 5%	3817
April	1st to 10th	Night	33% 4 11% 21% 18% 13%	2090
	11th to 20th	Night	37% 5% 9% 18% 18% 13%	1875
	21st to end	Night	32% 4 10% 21% 28% 5%	1900
May	1st to 10th	Night	45% 5% 11% 21% 13% 5%	2917
	11th to 20th	Night	38% 3 13% 19% 23% 3	2824
	21st to end	Night	36% 5% 16% 27% 13% 3	3099
June	1st to 10th	Night	21% 7% 17% 30% 21% 3	1710
	11th to 20th	Night	19% 5% 16% 33% 21% 5%	1710
	21st to end	Night	24% 5% 15% 27% 25% 4	1710
July	1st to 10th	Night	27% 5% 25% 35% 7%	2805
	11th to 20th	Night	17% 4 21% 38% 18% 2	2796
	21st to end	Night	37% 7% 18% 29% 9% 1	2999
August	1st to 10th	Night	10% 3 14% 33% 33% 7%	2826
	11th to 20th	Night	16% 4 17% 45% 15% 3	2902
	21st to end	Night	22% 7% 19% 29% 19% 3	3476
September	1st to 10th	Night	29% 6% 12% 24% 19% 10%	2048
	11th to 20th	Night	30% 5% 11% 23% 20% 10%	2024
	21st to end	Night	22% 4 9% 21% 30% 13%	1980
October	1st to 10th	Night	22% 3 10% 25% 22% 18%	2092
	11th to 20th	Night	27% 3 6% 17% 27% 20%	2160
	21st to end	Night	31% 3 5% 17% 27% 18%	2376
November	1st to 10th	Night	28% 3 9% 20% 27% 13%	2220
	11th to 20th	Night	31% 3 7% 19% 26% 14%	2280
	21st to end	Night	38% 3 7% 17% 24% 11%	2436
December	1st to 10th	Night	37% 4 9% 19% 21% 10%	2470
	11th to 20th	Night	41% 3 6% 14% 24% 13%	3037
	21st to end	Night	39% 3 5% 16% 27% 10%	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	23% 12% 37% 20% 8%	270
	11th to 20th	Day	22% 15% 39% 16% 9%	270
	21st to end	Day	23% 15% 38% 17% 6%	297
February	1st to 10th	Day	28% 11% 35% 19% 5% 1	270
	11th to 20th	Day	31% 17% 35% 13% 3	270
	21st to end	Day	29% 20% 39% 10% 3	225
March	1st to 10th	Day	22% 15% 34% 23% 5% 1	270
	11th to 20th	Day	20% 21% 35% 20% 4	270
	21st to end	Day	16% 18% 39% 20% 7%	297
April	1st to 10th	Day	19% 15% 37% 24% 4 1	270
	11th to 20th	Day	23% 13% 27% 25% 11% 2	450
	21st to end	Day	16% 11% 34% 27% 10% 2	460
May	1st to 10th	Day	13% 9% 33% 34% 10%	605
	11th to 20th	Day	14% 5% 23% 36% 18% 4	675
	21st to end	Day	12% 6% 23% 35% 19% 5%	734
June	1st to 10th	Day	8% 3 10% 36% 35% 9%	680
	11th to 20th	Day	5% 2 13% 39% 32% 10%	680
	21st to end	Day	5% 2 9% 32% 34% 18%	680
July	1st to 10th	Day	6% 3 7% 30% 39% 15%	671
	11th to 20th	Day	3 1 4 29% 44% 19%	668
	21st to end	Day	6% 1 4 28% 45% 16%	739
August	1st to 10th	Day	4 1 5% 24% 48% 19%	676
	11th to 20th	Day	6% 1 3 29% 45% 16%	622
	21st to end	Day	10% 1 4 21% 36% 27%	539
September	1st to 10th	Day	7% 1 6% 23% 39% 23%	336
	11th to 20th	Day	6% 2 8% 31% 33% 21%	279
	21st to end	Day	9% 3 7% 29% 33% 19%	270
October	1st to 10th	Day	6% 1 15% 37% 34% 7%	270
	11th to 20th	Day	11% 5% 28% 30% 19% 7%	270
	21st to end	Day	25% 9% 25% 26% 12% 3	297
November	1st to 10th	Day	17% 8% 25% 31% 16% 3	270
	11th to 20th	Day	12% 10% 30% 34% 11% 3	270
	21st to end	Day	20% 13% 31% 26% 10% 1	270
December	1st to 10th	Day	18% 13% 30% 27% 9% 3	270
	11th to 20th	Day	24% 12% 34% 23% 7%	270
	21st to end	Day	22% 16% 35% 21% 4 1	297
January	1st to 10th	Night	18% 11% 35% 29% 7%	950
	11th to 20th	Night	22% 13% 31% 28% 6%	950
	21st to end	Night	21% 9% 36% 29% 5%	1045
February	1st to 10th	Night	21% 12% 33% 28% 5%	950
	11th to 20th	Night	24% 13% 36% 24% 3	757
	21st to end	Night	22% 16% 40% 20% 2	490
March	1st to 10th	Night	19% 11% 36% 28% 6%	570
	11th to 20th	Night	16% 10% 38% 28% 6% 1	570
	21st to end	Night	14% 10% 39% 30% 7%	627
April	1st to 10th	Night	12% 11% 41% 29% 6%	570
	11th to 20th	Night	14% 13% 37% 26% 10% 1	563
	21st to end	Night	12% 10% 41% 26% 10% 1	570
May	1st to 10th	Night	11% 6% 40% 32% 10% 1	570
	11th to 20th	Night	10% 6% 28% 37% 17% 2	561
	21st to end	Night	9% 4 26% 38% 21% 1	617
June	1st to 10th	Night	6% 1 12% 44% 34% 4	570
	11th to 20th	Night	3 2 16% 47% 30% 2	570
	21st to end	Night	4 2 11% 36% 39% 8%	570
July	1st to 10th	Night	3 2 7% 40% 42% 6%	555
	11th to 20th	Night	3 1 5% 38% 48% 6%	552
	21st to end	Night	4 1 5% 38% 46% 6%	624
August	1st to 10th	Night	3 1 4 37% 50% 6%	567
	11th to 20th	Night	6% 4 38% 44% 8%	564
	21st to end	Night	5% 1 5% 34% 48% 8%	627
September	1st to 10th	Night	10% 1 7% 30% 45% 7%	570
	11th to 20th	Night	13% 1 7% 32% 42% 5%	552
	21st to end	Night	7% 1 9% 39% 39% 4	540
October	1st to 10th	Night	6% 2 14% 46% 27% 5%	652
	11th to 20th	Night	13% 5% 23% 40% 16% 3	720
	21st to end	Night	16% 7% 28% 29% 18% 2	792
November	1st to 10th	Night	12% 3 26% 41% 16% 1	740
	11th to 20th	Night	11% 9% 31% 38% 12%	760
	21st to end	Night	18% 11% 30% 28% 12% 1	916
December	1st to 10th	Night	17% 10% 31% 34% 8%	950
	11th to 20th	Night	20% 10% 30% 34% 5%	950
	21st to end	Night	19% 11% 33% 31% 6%	1045

Page generated at 2024-09-11 09:00:06. Version ac07

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