Lajitas
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Lajitas clear sky chart from 2005-11-06 to 2024-11-25.

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	3 3 1 3 3 3 3 3 5% 7% 67%	104582
	Night	4 3 1 3 3 3 3 3 6% 8% 64%	103578
Transparency	Day	11% 28% 6% 14% 19% 21%	104368
	Night	12% 29% 6% 14% 18% 21%	103381
Seeing	Day	5% 5% 18% 33% 30% 10%	14383
	Night	5% 3 18% 47% 25% 2	24622

By Month

Percentage Cloud Cover SW (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	3 2 1 2 2 2 2 2 4 5% 74%	3167
	11th to 20th	Day	4 2 1 2 2 1 2 2 3 5% 74%	3170
	21st to end	Day	4 5% 2 4 3 3 3 2 4 7% 62%	3487
February	1st to 10th	Day	3 4 2 4 4 3 4 2 5% 5% 64%	1900
	11th to 20th	Day	4 5% 2 5% 3 3 3 2 4 6% 63%	1849
	21st to end	Day	3 3 1 2 2 3 3 3 4 6% 69%	1570
March	1st to 10th	Day	2 3 2 4 3 3 4 4 5% 7% 62%	3130
	11th to 20th	Day	9% 4 1 3 3 3 3 3 5% 6% 60%	3357
	21st to end	Day	2 2 1 3 2 3 3 3 5% 7% 67%	4151
April	1st to 10th	Day	2 2 1 3 3 3 3 3 6% 7% 68%	2280
	11th to 20th	Day	2 3 1 2 2 3 3 3 5% 6% 71%	2251
	21st to end	Day	3 3 1 3 3 2 2 2 4 5% 71%	2280
May	1st to 10th	Day	1 2 1 2 1 2 2 2 3 6% 79%	3800
	11th to 20th	Day	2 2 1 2 2 3 3 3 4 6% 73%	3765
	21st to end	Day	1 1 2 1 2 2 3 5% 7% 75%	4255
June	1st to 10th	Day	1 1 1 2 2 3 4 6% 7% 72%	2470
	11th to 20th	Day	2 2 1 3 2 4 3 3 6% 8% 66%	2470
	21st to end	Day	2 2 1 3 3 3 4 4 8% 9% 62%	2337
July	1st to 10th	Day	2 2 1 3 3 4 4 4 6% 9% 62%	3800
	11th to 20th	Day	2 2 1 3 3 3 3 4 8% 11% 60%	3800
	21st to end	Day	3 2 1 3 3 3 4 5% 6% 11% 59%	4118
August	1st to 10th	Day	2 1 2 2 2 3 4 6% 11% 66%	3784
	11th to 20th	Day	3 2 1 4 3 4 4 3 7% 9% 61%	3726
	21st to end	Day	3 2 1 3 3 3 5% 4 7% 10% 59%	4180
September	1st to 10th	Day	6% 5% 2 6% 4 4 5% 4 8% 10% 47%	2280
	11th to 20th	Day	8% 6% 2 5% 3 3 4 4 7% 9% 50%	2152
	21st to end	Day	5% 3 2 4 3 3 4 3 5% 6% 62%	2090
October	1st to 10th	Day	2 1 2 2 2 2 2 3 5% 79%	3480
	11th to 20th	Day	4 2 1 2 2 2 3 2 5% 6% 73%	3319
	21st to end	Day	3 2 1 1 1 1 1 1 2 3 84%	3438
November	1st to 10th	Day	6% 2 1 3 2 1 2 2 4 5% 73%	1942
	11th to 20th	Day	4 3 1 3 2 2 3 2 5% 5% 70%	1800
	21st to end	Day	5% 3 1 4 2 3 3 3 5% 6% 66%	1746
December	1st to 10th	Day	5% 6% 1 3 3 3 3 2 4 7% 63%	1710
	11th to 20th	Day	3 5% 2 5% 4 4 4 3 6% 8% 57%	2161
	21st to end	Day	3 3 1 3 3 2 4 3 6% 8% 65%	3367
January	1st to 10th	Night	3 2 1 2 1 2 2 2 3 4 78%	3788
	11th to 20th	Night	4 2 2 1 2 2 2 3 6% 76%	3800
	21st to end	Night	6% 6% 2 4 3 3 4 3 6% 7% 57%	4180
February	1st to 10th	Night	4 4 1 4 2 3 4 3 4 6% 65%	2280
	11th to 20th	Night	5% 4 1 4 3 3 4 3 5% 7% 61%	2218
	21st to end	Night	5% 3 1 3 3 3 4 3 4 6% 66%	1884
March	1st to 10th	Night	3 4 1 5% 3 4 4 3 5% 7% 60%	3734
	11th to 20th	Night	11% 4 1 3 2 2 2 3 5% 6% 60%	3601
	21st to end	Night	3 3 1 4 3 3 3 3 5% 6% 65%	3490
April	1st to 10th	Night	3 3 1 4 3 4 3 3 4 6% 66%	1900
	11th to 20th	Night	3 3 1 3 2 3 3 3 5% 6% 68%	1877
	21st to end	Night	3 3 1 2 3 2 3 3 4 5% 71%	1900
May	1st to 10th	Night	2 2 1 2 2 2 2 2 4 5% 76%	3170
	11th to 20th	Night	4 2 1 3 2 3 3 3 6% 6% 66%	3140
	21st to end	Night	2 2 1 3 3 3 3 3 5% 7% 67%	3328
June	1st to 10th	Night	2 2 1 3 3 4 4 5% 9% 11% 56%	1710
	11th to 20th	Night	2 2 1 4 4 4 5% 5% 9% 10% 54%	1710
	21st to end	Night	3 3 1 3 4 3 3 5% 8% 11% 57%	1831
July	1st to 10th	Night	2 2 1 4 3 4 6% 5% 9% 13% 51%	3170
	11th to 20th	Night	2 2 1 3 3 3 4 5% 8% 13% 57%	3170
	21st to end	Night	2 2 1 3 3 4 5% 5% 8% 10% 57%	3445
August	1st to 10th	Night	1 1 1 2 3 3 4 4 10% 14% 57%	3155
	11th to 20th	Night	2 2 1 3 3 4 4 5% 7% 13% 57%	3113
	21st to end	Night	2 2 1 3 4 4 5% 5% 8% 13% 52%	3487
September	1st to 10th	Night	4 3 1 6% 5% 5% 5% 4 7% 9% 49%	1900
	11th to 20th	Night	6% 4 2 7% 4 5% 6% 5% 7% 10% 43%	2028
	21st to end	Night	4 4 2 5% 4 4 5% 3 6% 10% 53%	2090
October	1st to 10th	Night	2 2 1 2 2 2 3 3 4 6% 73%	3480
	11th to 20th	Night	5% 2 1 3 2 3 3 2 5% 6% 69%	3586
	21st to end	Night	3 2 1 2 1 1 1 1 2 4 83%	4120
November	1st to 10th	Night	6% 2 1 2 2 1 1 2 4 4 76%	2340
	11th to 20th	Night	4 2 1 2 2 2 3 3 5% 5% 71%	2592
	21st to end	Night	5% 3 1 3 2 3 3 2 4 6% 66%	2529
December	1st to 10th	Night	6% 3 1 3 2 3 4 4 6% 6% 63%	2470
	11th to 20th	Night	3 4 1 4 3 3 4 3 5% 8% 63%	3036
	21st to end	Night	3 3 1 4 2 3 3 4 6% 8% 64%	4326

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	7% 27% 4 7% 24% 32%	3168
	11th to 20th	Day	8% 27% 3 12% 27% 22%	3170
	21st to end	Day	18% 25% 4 23% 20% 11%	3487
February	1st to 10th	Day	12% 39% 4 7% 15% 23%	1900
	11th to 20th	Day	13% 40% 3 8% 18% 17%	1859
	21st to end	Day	9% 37% 3 8% 19% 23%	1570
March	1st to 10th	Day	12% 23% 6% 8% 24% 27%	3130
	11th to 20th	Day	17% 22% 6% 11% 17% 27%	3357
	21st to end	Day	11% 20% 6% 6% 19% 37%	4151
April	1st to 10th	Day	10% 34% 5% 8% 14% 30%	2280
	11th to 20th	Day	8% 32% 4 8% 16% 31%	2254
	21st to end	Day	10% 33% 4 7% 15% 31%	2280
May	1st to 10th	Day	7% 21% 3 9% 16% 45%	3800
	11th to 20th	Day	9% 23% 6% 9% 17% 36%	3768
	21st to end	Day	6% 22% 5% 13% 15% 39%	4255
June	1st to 10th	Day	6% 34% 5% 15% 20% 19%	2470
	11th to 20th	Day	8% 35% 7% 10% 20% 21%	2470
	21st to end	Day	13% 36% 8% 14% 18% 11%	2337
July	1st to 10th	Day	13% 24% 14% 25% 18% 7%	3741
	11th to 20th	Day	13% 23% 10% 33% 16% 6%	3737
	21st to end	Day	16% 24% 11% 22% 17% 10%	3988
August	1st to 10th	Day	9% 23% 7% 26% 28% 7%	3772
	11th to 20th	Day	13% 23% 10% 30% 20% 4	3762
	21st to end	Day	14% 25% 12% 23% 19% 6%	4179
September	1st to 10th	Day	21% 37% 10% 12% 10% 9%	2280
	11th to 20th	Day	20% 36% 7% 13% 16% 8%	2152
	21st to end	Day	12% 35% 5% 14% 18% 16%	2090
October	1st to 10th	Day	6% 22% 4 9% 22% 38%	3480
	11th to 20th	Day	8% 21% 8% 17% 15% 31%	3319
	21st to end	Day	5% 21% 2 9% 35% 29%	3438
November	1st to 10th	Day	4 40% 3 11% 21% 21%	1942
	11th to 20th	Day	6% 42% 5% 11% 20% 16%	1800
	21st to end	Day	10% 44% 5% 14% 12% 15%	1746
December	1st to 10th	Day	11% 44% 5% 7% 20% 13%	1710
	11th to 20th	Day	16% 36% 4 14% 20% 10%	2159
	21st to end	Day	11% 27% 4 10% 27% 22%	3367
January	1st to 10th	Night	5% 26% 2 7% 28% 32%	3788
	11th to 20th	Night	7% 27% 4 10% 23% 30%	3800
	21st to end	Night	19% 26% 4 18% 21% 11%	4180
February	1st to 10th	Night	12% 38% 4 7% 16% 24%	2280
	11th to 20th	Night	15% 40% 4 7% 15% 19%	2218
	21st to end	Night	9% 38% 2 6% 19% 25%	1884
March	1st to 10th	Night	15% 23% 4 6% 20% 32%	3734
	11th to 20th	Night	19% 22% 6% 11% 17% 25%	3601
	21st to end	Night	14% 21% 6% 8% 18% 33%	3490
April	1st to 10th	Night	13% 34% 4 8% 13% 27%	1900
	11th to 20th	Night	10% 33% 5% 9% 14% 30%	1877
	21st to end	Night	11% 33% 4 9% 14% 28%	1900
May	1st to 10th	Night	9% 21% 3 9% 13% 45%	3170
	11th to 20th	Night	14% 24% 7% 10% 11% 34%	3141
	21st to end	Night	11% 23% 6% 12% 14% 34%	3329
June	1st to 10th	Night	10% 37% 9% 18% 14% 12%	1710
	11th to 20th	Night	14% 36% 7% 11% 16% 16%	1710
	21st to end	Night	15% 37% 8% 14% 16% 10%	1831
July	1st to 10th	Night	16% 24% 16% 24% 15% 4	3120
	11th to 20th	Night	13% 24% 12% 33% 14% 4	3110
	21st to end	Night	17% 25% 11% 23% 18% 6%	3336
August	1st to 10th	Night	10% 24% 7% 30% 26% 3	3144
	11th to 20th	Night	13% 23% 13% 33% 17% 2	3143
	21st to end	Night	16% 26% 14% 24% 18% 3	3487
September	1st to 10th	Night	20% 38% 12% 13% 9% 8%	1900
	11th to 20th	Night	23% 37% 9% 11% 13% 6%	2028
	21st to end	Night	15% 36% 8% 13% 14% 14%	2090
October	1st to 10th	Night	7% 22% 5% 8% 18% 39%	3480
	11th to 20th	Night	13% 22% 7% 15% 12% 31%	3586
	21st to end	Night	6% 21% 2 11% 33% 27%	4120
November	1st to 10th	Night	4 39% 2 9% 23% 23%	2340
	11th to 20th	Night	7% 42% 5% 9% 16% 21%	2592
	21st to end	Night	9% 43% 6% 11% 13% 17%	2529
December	1st to 10th	Night	11% 45% 5% 9% 16% 14%	2470
	11th to 20th	Night	12% 36% 4 15% 21% 12%	3037
	21st to end	Night	12% 27% 5% 10% 24% 22%	4326

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	12% 4 24% 38% 19% 3	270
	11th to 20th	Day	6% 5% 20% 42% 25% 1	270
	21st to end	Day	4 12% 27% 34% 21% 2	297
February	1st to 10th	Day	10% 9% 23% 31% 25% 3	270
	11th to 20th	Day	9% 11% 23% 36% 19% 1	270
	21st to end	Day	7% 12% 30% 39% 11% 2	225
March	1st to 10th	Day	6% 6% 31% 35% 20% 2	270
	11th to 20th	Day	8% 12% 33% 31% 11% 5%	379
	21st to end	Day	9% 14% 31% 32% 13% 1	506
April	1st to 10th	Day	4 15% 35% 33% 12% 1	460
	11th to 20th	Day	4 15% 40% 29% 10% 3	452
	21st to end	Day	6% 13% 31% 38% 11%	460
May	1st to 10th	Day	3 9% 32% 38% 14% 3	463
	11th to 20th	Day	2 9% 32% 39% 17% 2	488
	21st to end	Day	3 5% 26% 42% 22% 2	591
June	1st to 10th	Day	2 3 14% 37% 38% 6%	680
	11th to 20th	Day	3 10% 41% 40% 6%	680
	21st to end	Day	3 1 11% 34% 43% 10%	547
July	1st to 10th	Day	4 1 7% 25% 40% 23%	486
	11th to 20th	Day	2 5% 34% 40% 18%	484
	21st to end	Day	2 1 4 33% 42% 17%	531
August	1st to 10th	Day	2 1 4 21% 49% 23%	487
	11th to 20th	Day	4 1 7% 23% 40% 25%	477
	21st to end	Day	3 1 6% 25% 39% 26%	539
September	1st to 10th	Day	8% 1 7% 30% 38% 17%	490
	11th to 20th	Day	6% 5% 19% 47% 23%	362
	21st to end	Day	6% 2 7% 24% 40% 21%	300
October	1st to 10th	Day	4 2 9% 24% 41% 20%	300
	11th to 20th	Day	9% 2 9% 29% 32% 18%	300
	21st to end	Day	8% 3 12% 27% 34% 16%	330
November	1st to 10th	Day	7% 4 13% 31% 34% 12%	300
	11th to 20th	Day	9% 7% 15% 27% 31% 11%	300
	21st to end	Day	8% 8% 17% 35% 26% 6%	282
December	1st to 10th	Day	8% 6% 13% 32% 36% 6%	270
	11th to 20th	Day	4 9% 22% 39% 25% 1	270
	21st to end	Day	6% 6% 19% 44% 24% 1	297
January	1st to 10th	Night	6% 3 20% 53% 18% 1	760
	11th to 20th	Night	8% 3 18% 51% 19% 1	760
	21st to end	Night	7% 5% 23% 48% 16% 1	836
February	1st to 10th	Night	6% 4 25% 45% 19% 1	760
	11th to 20th	Night	7% 4 23% 54% 11% 1	744
	21st to end	Night	6% 5% 29% 52% 7%	628
March	1st to 10th	Night	6% 5% 31% 47% 10% 1	760
	11th to 20th	Night	8% 7% 24% 46% 15% 1	760
	21st to end	Night	5% 6% 33% 45% 10%	640
April	1st to 10th	Night	3 8% 32% 47% 10%	570
	11th to 20th	Night	3 8% 38% 44% 7%	563
	21st to end	Night	3 7% 34% 49% 7%	570
May	1st to 10th	Night	4 5% 30% 52% 10%	570
	11th to 20th	Night	5% 5% 27% 53% 10%	561
	21st to end	Night	2 3 26% 56% 12%	617
June	1st to 10th	Night	2 2 19% 56% 21% 1	570
	11th to 20th	Night	2 1 18% 54% 24%	570
	21st to end	Night	4 1 14% 45% 36%	570
July	1st to 10th	Night	4 1 11% 40% 41% 3	555
	11th to 20th	Night	3 5% 43% 47% 2	552
	21st to end	Night	3 1 6% 40% 47% 3	624
August	1st to 10th	Night	2 1 4 32% 58% 4	567
	11th to 20th	Night	3 1 4 30% 56% 5%	564
	21st to end	Night	4 6% 33% 53% 4	627
September	1st to 10th	Night	5% 1 6% 34% 51% 3	570
	11th to 20th	Night	8% 1 7% 36% 46% 2	570
	21st to end	Night	6% 1 9% 42% 40% 2	570
October	1st to 10th	Night	3 1 11% 45% 38% 2	570
	11th to 20th	Night	9% 1 10% 52% 26% 2	646
	21st to end	Night	6% 3 12% 43% 32% 4	836
November	1st to 10th	Night	6% 1 10% 46% 33% 4	780
	11th to 20th	Night	4 3 12% 49% 30% 1	992
	21st to end	Night	6% 3 21% 46% 21% 3	973
December	1st to 10th	Night	7% 2 13% 52% 25% 1	950
	11th to 20th	Night	5% 3 19% 53% 19% 1	950
	21st to end	Night	5% 4 20% 53% 15% 2	917

Page generated at 2024-11-22 07:02:26. Version ac07

Copyright © 2024 Attilla Danko.