Lipantitlan State Historic Site
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Lipantitlan State Historic Site clear sky chart from 2005-11-06 to 2025-06-10.

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 5% 4 6% 8% 44%	119889
	Night	15% 6% 2 5% 3 3 3 3 5% 7% 48%	118606
Transparency	Day	36% 7% 12% 21% 15% 9%	123710
	Night	35% 6% 13% 21% 15% 10%	122915
Seeing	Day	11% 6% 22% 31% 22% 7%	15300
	Night	15% 5% 23% 37% 19% 1	25318

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	20% 8% 3 6% 4 4 3 2 4 5% 41%	4077
	11th to 20th	Day	17% 5% 2 5% 3 3 3 3 5% 7% 48%	4080
	21st to end	Day	27% 7% 2 6% 3 2 3 3 5% 6% 34%	4966
February	1st to 10th	Day	19% 8% 3 7% 4 4 4 3 4 6% 39%	2000
	11th to 20th	Day	19% 8% 3 6% 4 3 4 2 4 5% 43%	1949
	21st to end	Day	18% 7% 3 5% 5% 2 3 3 5% 5% 45%	1673
March	1st to 10th	Day	13% 7% 2 6% 4 3 4 4 4 7% 44%	4936
	11th to 20th	Day	17% 7% 3 7% 4 3 3 2 4 5% 46%	4980
	21st to end	Day	13% 6% 2 5% 4 3 4 3 5% 7% 47%	5462
April	1st to 10th	Day	12% 6% 3 6% 4 4 4 4 6% 7% 45%	2200
	11th to 20th	Day	16% 7% 2 6% 5% 4 4 3 5% 6% 42%	2176
	21st to end	Day	12% 7% 2 6% 5% 4 5% 4 6% 8% 42%	2394
May	1st to 10th	Day	14% 7% 3 8% 5% 5% 5% 4 7% 9% 32%	5862
	11th to 20th	Day	6% 5% 2 6% 4 4 5% 4 6% 8% 51%	5862
	21st to end	Day	7% 5% 2 6% 5% 5% 6% 4 7% 9% 44%	6434
June	1st to 10th	Day	5% 4 2 4 3 5% 5% 4 8% 10% 51%	2588
	11th to 20th	Day	4 4 1 6% 5% 5% 6% 5% 7% 10% 47%	2470
	21st to end	Day	7% 5% 2 6% 6% 5% 7% 4 9% 10% 38%	2470
July	1st to 10th	Day	6% 5% 2 6% 5% 6% 6% 5% 7% 10% 43%	4120
	11th to 20th	Day	5% 7% 3 8% 7% 7% 7% 6% 8% 10% 33%	4120
	21st to end	Day	8% 6% 3 7% 6% 5% 5% 5% 7% 10% 37%	4465
August	1st to 10th	Day	1 2 1 2 3 3 3 3 6% 9% 68%	3986
	11th to 20th	Day	2 2 1 5% 3 4 6% 6% 9% 13% 48%	3726
	21st to end	Day	4 5% 2 7% 6% 6% 6% 5% 9% 12% 38%	3899
September	1st to 10th	Day	9% 6% 3 8% 7% 7% 6% 5% 7% 9% 33%	2090
	11th to 20th	Day	10% 6% 3 8% 6% 6% 6% 5% 6% 8% 37%	2090
	21st to end	Day	8% 4 2 6% 5% 5% 5% 4 6% 9% 46%	2090
October	1st to 10th	Day	6% 4 1 5% 5% 5% 4 4 6% 8% 51%	2090
	11th to 20th	Day	11% 5% 2 5% 4 5% 4 4 5% 7% 49%	1969
	21st to end	Day	9% 4 2 5% 4 4 4 4 4 5% 57%	2090
November	1st to 10th	Day	11% 6% 3 6% 5% 5% 4 3 6% 7% 44%	1958
	11th to 20th	Day	14% 6% 3 5% 5% 4 4 3 5% 6% 47%	1998
	21st to end	Day	16% 7% 4 7% 4 3 4 4 5% 5% 42%	1800
December	1st to 10th	Day	31% 11% 3 6% 4 3 2 2 3 4 31%	2940
	11th to 20th	Day	13% 7% 2 8% 4 5% 5% 4 6% 6% 40%	3391
	21st to end	Day	12% 5% 2 6% 4 4 4 2 4 6% 51%	4488
January	1st to 10th	Night	23% 8% 2 5% 3 2 3 2 3 5% 44%	5888
	11th to 20th	Night	16% 5% 2 6% 3 3 3 3 5% 6% 50%	5900
	21st to end	Night	30% 7% 3 6% 4 3 3 3 5% 5% 31%	6056
February	1st to 10th	Night	18% 7% 2 6% 4 4 4 4 5% 5% 42%	2400
	11th to 20th	Night	20% 7% 2 4 2 3 3 3 5% 7% 44%	2338
	21st to end	Night	19% 8% 2 4 3 3 3 3 4 5% 45%	1955
March	1st to 10th	Night	21% 7% 2 5% 3 3 4 3 5% 6% 41%	4919
	11th to 20th	Night	18% 7% 3 6% 4 3 3 2 3 4 46%	4980
	21st to end	Night	20% 7% 2 4 3 2 3 2 3 5% 49%	5467
April	1st to 10th	Night	14% 6% 3 8% 4 4 4 3 5% 8% 40%	2200
	11th to 20th	Night	17% 7% 2 5% 4 3 3 4 4 7% 44%	2173
	21st to end	Night	18% 8% 3 6% 4 3 3 4 6% 5% 39%	1997
May	1st to 10th	Night	25% 9% 3 6% 5% 4 4 4 5% 6% 30%	4053
	11th to 20th	Night	12% 6% 2 4 3 3 3 2 5% 8% 50%	4053
	21st to end	Night	11% 9% 3 8% 5% 5% 5% 4 6% 10% 35%	4443
June	1st to 10th	Night	5% 3 1 3 2 3 4 4 7% 10% 57%	1796
	11th to 20th	Night	3 4 2 4 4 4 4 4 5% 10% 56%	1710
	21st to end	Night	5% 3 2 4 4 4 5% 4 7% 11% 51%	1710
July	1st to 10th	Night	5% 4 1 4 3 3 4 3 7% 11% 55%	2850
	11th to 20th	Night	4 4 2 6% 5% 5% 7% 5% 7% 12% 42%	2850
	21st to end	Night	7% 6% 2 5% 4 4 4 5% 8% 11% 46%	3098
August	1st to 10th	Night	1 1 1 1 1 2 2 3 6% 82%	2949
	11th to 20th	Night	3 3 1 4 2 3 3 4 7% 12% 59%	3113
	21st to end	Night	3 3 1 3 3 2 4 3 6% 12% 61%	3756
September	1st to 10th	Night	7% 6% 2 7% 4 4 4 4 7% 9% 47%	2090
	11th to 20th	Night	9% 6% 3 6% 4 4 4 3 6% 9% 48%	2090
	21st to end	Night	7% 4 2 4 3 3 3 3 4 9% 56%	2090
October	1st to 10th	Night	4 3 1 4 3 3 3 3 6% 6% 64%	2090
	11th to 20th	Night	11% 3 1 4 3 3 3 2 4 6% 60%	2190
	21st to end	Night	9% 4 1 4 2 2 3 2 3 4 65%	2508
November	1st to 10th	Night	11% 5% 1 5% 4 3 3 3 5% 6% 53%	2340
	11th to 20th	Night	14% 5% 2 5% 3 3 2 2 4 6% 54%	2400
	21st to end	Night	17% 6% 2 5% 4 3 4 3 4 5% 46%	2598
December	1st to 10th	Night	35% 11% 3 5% 3 2 2 2 3 3 30%	4250
	11th to 20th	Night	15% 7% 2 6% 4 3 4 3 4 6% 47%	4816
	21st to end	Night	11% 6% 2 5% 3 3 3 3 4 6% 55%	6490

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	45% 4 7% 14% 20% 10%	4078
	11th to 20th	Day	37% 3 7% 20% 22% 11%	4080
	21st to end	Day	51% 3 6% 12% 16% 11%	4966
February	1st to 10th	Day	46% 5% 7% 9% 19% 15%	2000
	11th to 20th	Day	44% 4 9% 16% 17% 11%	1959
	21st to end	Day	41% 4 8% 18% 18% 11%	1673
March	1st to 10th	Day	39% 5% 8% 18% 11% 18%	4936
	11th to 20th	Day	41% 4 6% 9% 18% 23%	4980
	21st to end	Day	36% 6% 9% 22% 17% 10%	5464
April	1st to 10th	Day	37% 7% 11% 16% 17% 12%	2200
	11th to 20th	Day	42% 6% 8% 17% 14% 12%	2176
	21st to end	Day	39% 8% 9% 19% 14% 10%	2394
May	1st to 10th	Day	45% 8% 12% 20% 11% 4	5900
	11th to 20th	Day	29% 7% 13% 24% 18% 9%	5866
	21st to end	Day	32% 8% 11% 36% 12% 1	6447
June	1st to 10th	Day	26% 7% 15% 30% 19% 3	2588
	11th to 20th	Day	30% 7% 13% 26% 20% 4	2470
	21st to end	Day	37% 11% 16% 25% 10% 1	2470
July	1st to 10th	Day	33% 9% 22% 30% 6%	4056
	11th to 20th	Day	41% 10% 19% 21% 9%	4051
	21st to end	Day	38% 9% 22% 26% 4	4325
August	1st to 10th	Day	13% 6% 16% 45% 20%	3972
	11th to 20th	Day	21% 10% 31% 30% 7%	3762
	21st to end	Day	33% 11% 19% 26% 9% 1	3898
September	1st to 10th	Day	45% 11% 14% 14% 12% 4	2090
	11th to 20th	Day	41% 10% 15% 17% 14% 3	2090
	21st to end	Day	32% 9% 14% 19% 16% 10%	2090
October	1st to 10th	Day	23% 4 8% 12% 23% 31%	3480
	11th to 20th	Day	30% 5% 10% 16% 19% 20%	3248
	21st to end	Day	27% 5% 7% 17% 30% 14%	3428
November	1st to 10th	Day	37% 6% 11% 18% 19% 9%	1958
	11th to 20th	Day	37% 5% 10% 15% 18% 13%	1998
	21st to end	Day	44% 5% 8% 15% 16% 12%	1800
December	1st to 10th	Day	59% 3 6% 12% 16% 5%	2940
	11th to 20th	Day	42% 6% 7% 17% 15% 13%	3389
	21st to end	Day	34% 4 6% 21% 20% 14%	4488
January	1st to 10th	Night	43% 4 7% 14% 16% 16%	5888
	11th to 20th	Night	36% 2 7% 20% 20% 16%	5900
	21st to end	Night	54% 4 5% 11% 16% 10%	6056
February	1st to 10th	Night	43% 5% 9% 12% 14% 17%	2400
	11th to 20th	Night	41% 5% 9% 15% 18% 12%	2338
	21st to end	Night	41% 4 8% 20% 17% 10%	1955
March	1st to 10th	Night	44% 6% 8% 17% 12% 13%	4919
	11th to 20th	Night	42% 4 6% 9% 16% 22%	4980
	21st to end	Night	38% 3 11% 21% 18% 9%	5467
April	1st to 10th	Night	41% 7% 12% 18% 13% 10%	2200
	11th to 20th	Night	40% 6% 10% 16% 14% 13%	2173
	21st to end	Night	44% 7% 10% 17% 14% 9%	1997
May	1st to 10th	Night	54% 6% 10% 16% 10% 5%	4080
	11th to 20th	Night	32% 6% 14% 22% 18% 7%	4054
	21st to end	Night	42% 8% 16% 28% 6%	4452
June	1st to 10th	Night	20% 7% 20% 34% 17% 2	1796
	11th to 20th	Night	22% 7% 14% 35% 20% 2	1710
	21st to end	Night	26% 10% 21% 32% 10% 1	1710
July	1st to 10th	Night	22% 8% 28% 37% 4	2805
	11th to 20th	Night	32% 11% 27% 23% 8%	2796
	21st to end	Night	30% 10% 29% 26% 5%	2999
August	1st to 10th	Night	7% 4 19% 52% 19%	2939
	11th to 20th	Night	18% 7% 37% 34% 4	3143
	21st to end	Night	17% 12% 30% 31% 9% 1	3756
September	1st to 10th	Night	33% 9% 22% 20% 12% 4	2090
	11th to 20th	Night	33% 8% 16% 26% 13% 3	2090
	21st to end	Night	25% 7% 14% 27% 18% 8%	2090
October	1st to 10th	Night	16% 5% 9% 19% 23% 29%	3480
	11th to 20th	Night	21% 4 13% 18% 29% 15%	3637
	21st to end	Night	22% 4 7% 22% 31% 14%	4120
November	1st to 10th	Night	31% 7% 12% 20% 21% 9%	2340
	11th to 20th	Night	33% 5% 13% 17% 18% 13%	2400
	21st to end	Night	39% 5% 10% 19% 16% 10%	2598
December	1st to 10th	Night	60% 3 6% 10% 13% 7%	4250
	11th to 20th	Night	39% 5% 8% 18% 14% 15%	4817
	21st to end	Night	32% 5% 7% 19% 21% 16%	6490

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	21% 9% 33% 25% 10% 2	300
	11th to 20th	Day	22% 9% 32% 24% 11% 1	300
	21st to end	Day	23% 11% 37% 17% 11% 1	330
February	1st to 10th	Day	21% 11% 27% 26% 12% 3	300
	11th to 20th	Day	23% 14% 33% 23% 7%	300
	21st to end	Day	21% 12% 40% 20% 6%	249
March	1st to 10th	Day	20% 11% 37% 23% 8%	300
	11th to 20th	Day	17% 13% 41% 23% 6%	300
	21st to end	Day	14% 12% 41% 28% 4 1	330
April	1st to 10th	Day	12% 13% 40% 25% 9% 1	300
	11th to 20th	Day	15% 15% 37% 21% 11% 1	294
	21st to end	Day	14% 11% 40% 29% 6%	494
May	1st to 10th	Day	12% 12% 44% 24% 7%	703
	11th to 20th	Day	9% 7% 39% 31% 11% 2	725
	21st to end	Day	8% 6% 33% 38% 15% 1	789
June	1st to 10th	Day	6% 2 17% 41% 29% 5%	726
	11th to 20th	Day	6% 1 16% 44% 27% 5%	680
	21st to end	Day	8% 2 12% 39% 27% 12%	680
July	1st to 10th	Day	6% 2 10% 37% 35% 11%	671
	11th to 20th	Day	4 2 5% 38% 42% 10%	668
	21st to end	Day	6% 1 7% 37% 37% 13%	739
August	1st to 10th	Day	1 5% 40% 37% 17%	610
	11th to 20th	Day	3 7% 41% 33% 16%	477
	21st to end	Day	6% 1 5% 27% 33% 29%	375
September	1st to 10th	Day	10% 1 9% 21% 38% 21%	300
	11th to 20th	Day	8% 3 23% 43% 23%	300
	21st to end	Day	6% 7% 24% 40% 23%	300
October	1st to 10th	Day	7% 3 8% 30% 39% 14%	300
	11th to 20th	Day	12% 1 12% 31% 28% 15%	300
	21st to end	Day	12% 8% 22% 32% 18% 8%	330
November	1st to 10th	Day	15% 4 18% 32% 26% 4	300
	11th to 20th	Day	19% 6% 18% 28% 26% 4	300
	21st to end	Day	22% 12% 25% 23% 14% 4	300
December	1st to 10th	Day	22% 6% 20% 32% 14% 6%	300
	11th to 20th	Day	18% 14% 26% 26% 13% 3	300
	21st to end	Day	16% 10% 31% 29% 12% 2	330
January	1st to 10th	Night	23% 7% 28% 31% 10% 1	1000
	11th to 20th	Night	21% 8% 30% 33% 8%	1000
	21st to end	Night	23% 8% 27% 35% 7%	913
February	1st to 10th	Night	22% 10% 31% 32% 5%	800
	11th to 20th	Night	26% 8% 30% 31% 5%	784
	21st to end	Night	23% 10% 39% 25% 4	635
March	1st to 10th	Night	23% 10% 32% 31% 4 1	600
	11th to 20th	Night	20% 9% 37% 30% 4	600
	21st to end	Night	16% 8% 39% 31% 5%	660
April	1st to 10th	Night	15% 8% 41% 31% 5%	600
	11th to 20th	Night	21% 8% 36% 29% 7%	593
	21st to end	Night	19% 8% 42% 25% 6%	600
May	1st to 10th	Night	17% 7% 42% 31% 3	600
	11th to 20th	Night	14% 3 36% 38% 8% 1	591
	21st to end	Night	10% 3 33% 41% 14%	650
June	1st to 10th	Night	4 2 17% 53% 24% 1	599
	11th to 20th	Night	5% 1 19% 56% 18% 1	570
	21st to end	Night	5% 1 16% 46% 29% 3	570
July	1st to 10th	Night	6% 1 9% 50% 32% 2	555
	11th to 20th	Night	3 1 6% 48% 40% 2	552
	21st to end	Night	3 2 7% 48% 39% 2	624
August	1st to 10th	Night	1 4 49% 43% 4	567
	11th to 20th	Night	5% 1 4 46% 40% 3	564
	21st to end	Night	4 1 4 32% 52% 7%	627
September	1st to 10th	Night	8% 1 5% 36% 44% 7%	570
	11th to 20th	Night	9% 1 4 29% 49% 7%	570
	21st to end	Night	9% 1 7% 33% 45% 5%	570
October	1st to 10th	Night	4 1 7% 37% 48% 3	570
	11th to 20th	Night	12% 1 16% 44% 24% 2	670
	21st to end	Night	9% 5% 24% 39% 22% 1	836
November	1st to 10th	Night	12% 5% 18% 41% 23% 1	780
	11th to 20th	Night	15% 4 25% 36% 19% 1	800
	21st to end	Night	19% 6% 24% 34% 16% 1	998
December	1st to 10th	Night	21% 6% 22% 37% 12% 2	1000
	11th to 20th	Night	23% 8% 27% 33% 10%	1000
	21st to end	Night	19% 7% 28% 36% 10% 1	1100

Page generated at 2025-06-07 09:28:19. Version ac07

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