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 2026-10-14.

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	11% 6% 2 6% 4 4 4 4 6% 8% 45%	148952
	Night	14% 6% 2 5% 3 3 3 3 5% 7% 48%	143183
Transparency	Day	35% 6% 13% 23% 14% 8%	152731
	Night	35% 6% 14% 22% 15% 9%	147471
Seeing	Day	11% 6% 22% 32% 22% 7%	17125
	Night	14% 5% 23% 37% 19% 1	26986

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	17% 7% 3 7% 4 3 3 2 3 5% 46%	5289
	11th to 20th	Day	16% 6% 2 6% 3 3 3 2 4 5% 49%	5310
	21st to end	Day	25% 8% 2 6% 3 2 3 3 4 5% 37%	6426
February	1st to 10th	Day	18% 8% 3 7% 4 4 3 3 4 6% 41%	2100
	11th to 20th	Day	18% 8% 3 6% 4 3 4 3 4 6% 43%	2049
	21st to end	Day	17% 7% 3 5% 4 2 3 3 5% 5% 47%	1754
March	1st to 10th	Day	13% 7% 3 6% 4 3 4 3 4 7% 44%	5046
	11th to 20th	Day	16% 7% 3 6% 4 3 3 2 4 5% 47%	5090
	21st to end	Day	13% 6% 2 5% 4 3 4 3 5% 7% 47%	5583
April	1st to 10th	Day	12% 6% 3 6% 4 4 4 4 6% 7% 44%	2310
	11th to 20th	Day	17% 6% 2 6% 5% 5% 5% 3 5% 6% 40%	2286
	21st to end	Day	12% 7% 2 6% 5% 4 5% 4 6% 8% 41%	2513
May	1st to 10th	Day	16% 7% 3 8% 5% 5% 5% 4 6% 9% 32%	7617
	11th to 20th	Day	6% 5% 2 6% 4 5% 5% 4 6% 8% 48%	7627
	21st to end	Day	9% 6% 2 7% 5% 5% 6% 4 7% 9% 39%	8392
June	1st to 10th	Day	5% 4 2 5% 4 5% 5% 4 8% 10% 49%	2730
	11th to 20th	Day	5% 4 2 6% 5% 5% 6% 5% 7% 10% 46%	2730
	21st to end	Day	7% 5% 2 6% 5% 5% 7% 4 9% 10% 40%	2730
July	1st to 10th	Day	6% 5% 2 6% 5% 5% 6% 5% 8% 11% 42%	7680
	11th to 20th	Day	5% 7% 3 8% 6% 6% 6% 5% 7% 11% 36%	7680
	21st to end	Day	5% 4 2 5% 4 4 5% 4 6% 11% 50%	8337
August	1st to 10th	Day	1 2 1 2 3 3 4 4 7% 10% 65%	5836
	11th to 20th	Day	2 2 1 4 3 3 5% 5% 9% 13% 53%	5483
	21st to end	Day	3 3 1 5% 4 5% 5% 5% 8% 12% 48%	5665
September	1st to 10th	Day	8% 6% 3 8% 7% 7% 6% 5% 7% 9% 35%	2310
	11th to 20th	Day	10% 6% 3 7% 5% 5% 6% 5% 7% 9% 38%	2310
	21st to end	Day	7% 4 2 6% 5% 5% 5% 4 7% 10% 46%	2310
October	1st to 10th	Day	6% 4 1 5% 5% 5% 4 4 6% 8% 51%	2310
	11th to 20th	Day	10% 4 2 5% 3 5% 4 4 6% 7% 50%	2105
	21st to end	Day	9% 3 2 5% 4 3 4 4 4 5% 58%	2200
November	1st to 10th	Day	10% 6% 2 6% 5% 5% 4 3 6% 7% 46%	2058
	11th to 20th	Day	13% 5% 2 5% 4 4 4 3 5% 6% 49%	2098
	21st to end	Day	15% 7% 4 7% 4 3 4 3 5% 5% 41%	1890
December	1st to 10th	Day	30% 11% 2 6% 4 3 2 2 3 4 32%	3030
	11th to 20th	Day	13% 7% 2 8% 4 5% 5% 4 6% 6% 40%	3481
	21st to end	Day	12% 5% 2 6% 4 4 4 3 4 6% 51%	4587
January	1st to 10th	Night	19% 8% 2 5% 3 2 3 2 3 4 49%	7634
	11th to 20th	Night	14% 6% 2 6% 3 3 3 2 4 5% 51%	7680
	21st to end	Night	28% 8% 3 6% 4 3 3 3 5% 5% 33%	7832
February	1st to 10th	Night	18% 7% 2 5% 4 3 4 4 5% 5% 44%	2520
	11th to 20th	Night	20% 7% 2 4 2 3 3 3 5% 7% 45%	2458
	21st to end	Night	19% 8% 2 4 3 3 3 3 4 5% 46%	2050
March	1st to 10th	Night	22% 7% 2 5% 3 3 4 3 5% 6% 40%	5029
	11th to 20th	Night	18% 7% 2 6% 4 3 3 2 3 4 47%	5090
	21st to end	Night	19% 7% 2 4 3 2 2 2 3 6% 49%	5588
April	1st to 10th	Night	15% 6% 3 8% 5% 4 4 3 5% 8% 40%	2310
	11th to 20th	Night	18% 7% 2 5% 4 3 3 4 4 7% 42%	2283
	21st to end	Night	18% 8% 3 6% 4 3 4 4 6% 5% 38%	2097
May	1st to 10th	Night	26% 10% 3 6% 4 4 3 3 5% 6% 29%	5266
	11th to 20th	Night	14% 6% 2 5% 3 3 4 3 6% 9% 44%	5265
	21st to end	Night	13% 9% 3 8% 5% 5% 5% 4 6% 9% 34%	5793
June	1st to 10th	Night	6% 4 1 4 3 3 4 4 7% 10% 55%	1890
	11th to 20th	Night	4 4 2 4 4 4 4 4 5% 10% 55%	1890
	21st to end	Night	5% 3 2 4 4 4 5% 4 7% 12% 51%	1890
July	1st to 10th	Night	5% 5% 2 5% 4 4 4 4 7% 11% 50%	5308
	11th to 20th	Night	6% 5% 2 7% 5% 5% 6% 5% 7% 11% 41%	5307
	21st to end	Night	6% 4 1 4 3 3 3 4 6% 9% 55%	5770
August	1st to 10th	Night	1 1 1 1 2 2 3 8% 81%	4315
	11th to 20th	Night	3 2 1 4 2 3 3 4 6% 11% 60%	4583
	21st to end	Night	2 2 1 3 2 2 3 3 6% 11% 66%	5450
September	1st to 10th	Night	7% 5% 2 7% 4 4 4 4 7% 9% 47%	2310
	11th to 20th	Night	8% 5% 2 5% 4 4 4 3 6% 9% 49%	2310
	21st to end	Night	6% 4 2 4 3 3 4 4 5% 10% 55%	2310
October	1st to 10th	Night	5% 3 1 4 3 3 3 3 6% 6% 63%	2310
	11th to 20th	Night	10% 3 1 4 3 3 2 2 3 6% 62%	2338
	21st to end	Night	9% 4 1 4 2 2 3 2 3 4 66%	2640
November	1st to 10th	Night	10% 5% 1 5% 4 3 3 3 5% 6% 55%	2460
	11th to 20th	Night	14% 5% 2 5% 3 3 2 2 4 6% 55%	2520
	21st to end	Night	17% 6% 2 5% 4 3 4 3 4 5% 45%	2728
December	1st to 10th	Night	35% 11% 3 5% 3 2 2 2 3 3 30%	4380
	11th to 20th	Night	15% 7% 2 6% 4 3 4 3 4 6% 47%	4946
	21st to end	Night	11% 7% 2 5% 3 3 3 3 4 6% 54%	6633

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	42% 4 10% 16% 19% 10%	5290
	11th to 20th	Day	38% 3 5% 16% 24% 13%	5310
	21st to end	Day	50% 3 6% 14% 18% 9%	6426
February	1st to 10th	Day	45% 5% 7% 10% 19% 15%	2100
	11th to 20th	Day	43% 4 9% 16% 16% 10%	2059
	21st to end	Day	40% 4 7% 18% 20% 11%	1754
March	1st to 10th	Day	39% 5% 8% 18% 11% 18%	5046
	11th to 20th	Day	40% 4 6% 9% 18% 23%	5090
	21st to end	Day	35% 6% 9% 23% 18% 10%	5585
April	1st to 10th	Day	38% 7% 11% 16% 17% 11%	2310
	11th to 20th	Day	43% 6% 9% 17% 14% 11%	2286
	21st to end	Day	39% 8% 10% 19% 14% 10%	2513
May	1st to 10th	Day	47% 7% 12% 22% 10% 3	7655
	11th to 20th	Day	32% 7% 14% 24% 16% 7%	7631
	21st to end	Day	38% 8% 11% 32% 11% 1	8405
June	1st to 10th	Day	28% 8% 16% 29% 17% 3	2730
	11th to 20th	Day	31% 8% 14% 25% 20% 3	2730
	21st to end	Day	35% 10% 16% 26% 11% 1	2730
July	1st to 10th	Day	34% 8% 27% 27% 4	7616
	11th to 20th	Day	39% 10% 24% 21% 6%	7611
	21st to end	Day	27% 7% 19% 37% 9%	8155
August	1st to 10th	Day	14% 7% 18% 45% 16%	5822
	11th to 20th	Day	18% 9% 31% 36% 6%	5519
	21st to end	Day	26% 9% 20% 35% 10% 1	5664
September	1st to 10th	Day	43% 10% 15% 16% 12% 4	2310
	11th to 20th	Day	39% 10% 16% 20% 13% 3	2310
	21st to end	Day	31% 9% 13% 22% 15% 10%	2310
October	1st to 10th	Day	23% 4 8% 12% 23% 29%	3700
	11th to 20th	Day	29% 5% 10% 17% 20% 19%	3384
	21st to end	Day	26% 5% 7% 18% 29% 15%	3538
November	1st to 10th	Day	36% 6% 10% 17% 20% 11%	2058
	11th to 20th	Day	36% 5% 10% 16% 18% 14%	2098
	21st to end	Day	44% 5% 8% 15% 16% 11%	1890
December	1st to 10th	Day	58% 3 6% 12% 16% 5%	3030
	11th to 20th	Day	42% 6% 7% 17% 15% 13%	3479
	21st to end	Day	34% 4 6% 21% 20% 14%	4587
January	1st to 10th	Night	39% 3 10% 16% 18% 14%	7635
	11th to 20th	Night	36% 2 5% 18% 20% 18%	7680
	21st to end	Night	53% 4 6% 13% 16% 9%	7832
February	1st to 10th	Night	41% 5% 10% 12% 15% 17%	2520
	11th to 20th	Night	40% 5% 10% 17% 17% 12%	2458
	21st to end	Night	40% 4 8% 20% 18% 10%	2050
March	1st to 10th	Night	45% 5% 8% 17% 12% 13%	5029
	11th to 20th	Night	42% 4 6% 10% 16% 22%	5090
	21st to end	Night	37% 3 11% 21% 18% 9%	5588
April	1st to 10th	Night	42% 7% 12% 17% 12% 9%	2310
	11th to 20th	Night	41% 6% 10% 16% 13% 13%	2283
	21st to end	Night	45% 7% 10% 16% 13% 9%	2097
May	1st to 10th	Night	55% 6% 11% 16% 9% 3	5293
	11th to 20th	Night	36% 6% 14% 23% 16% 5%	5266
	21st to end	Night	45% 8% 16% 26% 5%	5805
June	1st to 10th	Night	22% 7% 20% 32% 17% 1	1890
	11th to 20th	Night	24% 7% 14% 34% 19% 2	1890
	21st to end	Night	25% 10% 22% 31% 11% 1	1890
July	1st to 10th	Night	28% 8% 31% 31% 2	5265
	11th to 20th	Night	36% 10% 29% 21% 4	5256
	21st to end	Night	25% 7% 23% 34% 10% 1	5641
August	1st to 10th	Night	6% 4 25% 50% 16%	4305
	11th to 20th	Night	18% 7% 37% 34% 3	4613
	21st to end	Night	13% 9% 29% 38% 10%	5450
September	1st to 10th	Night	32% 9% 23% 21% 11% 4	2310
	11th to 20th	Night	32% 8% 18% 27% 12% 3	2310
	21st to end	Night	25% 7% 15% 29% 17% 7%	2310
October	1st to 10th	Night	17% 5% 9% 19% 23% 28%	3700
	11th to 20th	Night	21% 4 12% 20% 29% 14%	3785
	21st to end	Night	22% 4 8% 22% 31% 14%	4252
November	1st to 10th	Night	30% 7% 11% 19% 23% 10%	2460
	11th to 20th	Night	32% 5% 13% 18% 18% 14%	2520
	21st to end	Night	40% 5% 10% 19% 16% 9%	2728
December	1st to 10th	Night	60% 3 6% 10% 13% 8%	4380
	11th to 20th	Night	39% 5% 8% 18% 15% 15%	4947
	21st to end	Night	32% 5% 7% 19% 20% 16%	6633

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	20% 9% 32% 24% 11% 3	330
	11th to 20th	Day	23% 9% 31% 25% 12% 1	330
	21st to end	Day	23% 12% 36% 18% 11% 1	363
February	1st to 10th	Day	20% 11% 27% 27% 12% 3	330
	11th to 20th	Day	21% 14% 33% 25% 7% 1	330
	21st to end	Day	19% 11% 40% 22% 6% 1	273
March	1st to 10th	Day	18% 12% 37% 24% 8%	330
	11th to 20th	Day	16% 12% 41% 23% 7%	330
	21st to end	Day	13% 11% 39% 30% 6% 1	363
April	1st to 10th	Day	13% 13% 40% 25% 8% 1	330
	11th to 20th	Day	16% 15% 38% 21% 10% 1	324
	21st to end	Day	14% 11% 40% 29% 6%	533
May	1st to 10th	Day	14% 12% 43% 24% 7%	753
	11th to 20th	Day	9% 8% 39% 31% 11% 2	775
	21st to end	Day	8% 6% 33% 37% 14% 1	844
June	1st to 10th	Day	6% 3 19% 41% 27% 5%	780
	11th to 20th	Day	7% 2 17% 44% 25% 5%	780
	21st to end	Day	7% 2 14% 40% 25% 11%	780
July	1st to 10th	Day	6% 2 10% 37% 33% 11%	771
	11th to 20th	Day	4 2 6% 40% 39% 9%	768
	21st to end	Day	5% 1 8% 37% 36% 13%	849
August	1st to 10th	Day	2 5% 39% 37% 17%	702
	11th to 20th	Day	3 1 8% 42% 31% 16%	557
	21st to end	Day	5% 1 4 27% 34% 29%	445
September	1st to 10th	Day	9% 1 8% 22% 38% 22%	360
	11th to 20th	Day	7% 1 3 27% 41% 21%	360
	21st to end	Day	5% 8% 26% 39% 22%	360
October	1st to 10th	Day	7% 3 8% 31% 38% 13%	360
	11th to 20th	Day	11% 1 11% 32% 30% 15%	339
	21st to end	Day	10% 8% 22% 31% 20% 8%	363
November	1st to 10th	Day	14% 5% 18% 32% 25% 6%	330
	11th to 20th	Day	17% 6% 19% 28% 26% 4	330
	21st to end	Day	21% 11% 26% 24% 14% 4	330
December	1st to 10th	Day	22% 7% 20% 32% 14% 5%	330
	11th to 20th	Day	19% 14% 24% 26% 15% 3	330
	21st to end	Day	15% 10% 29% 31% 12% 2	363
January	1st to 10th	Night	22% 7% 28% 32% 10% 1	1050
	11th to 20th	Night	20% 8% 30% 34% 8%	1050
	21st to end	Night	23% 8% 28% 34% 7%	958
February	1st to 10th	Night	21% 10% 30% 33% 5%	840
	11th to 20th	Night	25% 8% 31% 31% 5%	824
	21st to end	Night	23% 10% 38% 26% 4	666
March	1st to 10th	Night	24% 10% 31% 30% 4	630
	11th to 20th	Night	20% 8% 37% 30% 5%	630
	21st to end	Night	16% 8% 39% 32% 5%	693
April	1st to 10th	Night	16% 8% 41% 30% 5%	630
	11th to 20th	Night	22% 8% 36% 28% 7%	623
	21st to end	Night	19% 8% 43% 25% 5%	630
May	1st to 10th	Night	17% 7% 41% 31% 3	630
	11th to 20th	Night	15% 3 36% 37% 8% 1	621
	21st to end	Night	10% 3 32% 40% 14%	683
June	1st to 10th	Night	5% 2 17% 51% 24% 1	630
	11th to 20th	Night	6% 1 20% 54% 18% 1	630
	21st to end	Night	4 1 16% 47% 29% 3	630
July	1st to 10th	Night	7% 1 9% 50% 31% 2	615
	11th to 20th	Night	4 2 7% 48% 37% 2	612
	21st to end	Night	3 2 7% 49% 38% 2	690
August	1st to 10th	Night	1 3 49% 43% 4	627
	11th to 20th	Night	5% 2 5% 46% 39% 3	624
	21st to end	Night	4 1 4 33% 52% 7%	693
September	1st to 10th	Night	7% 1 4 37% 43% 7%	630
	11th to 20th	Night	9% 1 4 31% 49% 6%	630
	21st to end	Night	9% 1 7% 34% 44% 5%	630
October	1st to 10th	Night	4 1 7% 37% 48% 3	630
	11th to 20th	Night	11% 1 16% 43% 26% 2	714
	21st to end	Night	9% 5% 23% 40% 22% 1	880
November	1st to 10th	Night	12% 5% 18% 41% 23% 1	820
	11th to 20th	Night	15% 3 25% 37% 19% 1	840
	21st to end	Night	19% 6% 25% 33% 15% 1	1048
December	1st to 10th	Night	22% 6% 22% 37% 12% 1	1050
	11th to 20th	Night	23% 7% 26% 33% 10%	1050
	21st to end	Night	19% 7% 28% 36% 10% 1	1155

Page generated at 2026-10-11 04:06:31. Version ac07

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