Highpointe Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Highpointe Observatory clear sky chart from 2005-11-06 to 2024-01-16.

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% 3 6% 6% 4 5% 5% 6% 8% 40%	75020
	Night	11% 6% 2 5% 5% 3 4 5% 6% 8% 46%	74730
Transparency	Day	40% 8% 11% 16% 17% 6%	74756
	Night	35% 8% 12% 18% 19% 8%	74514
Seeing	Day	14% 9% 20% 25% 22% 10%	13636
	Night	14% 7% 22% 30% 22% 5%	23326

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	18% 7% 2 4 4 2 4 4 6% 6% 43%	1733
	11th to 20th	Day	17% 7% 2 5% 4 2 4 4 5% 5% 44%	1753
	21st to end	Day	18% 7% 3 5% 4 3 3 3 4 4 46%	1980
February	1st to 10th	Day	17% 8% 3 5% 5% 3 5% 4 5% 6% 38%	1800
	11th to 20th	Day	18% 6% 3 5% 4 2 4 4 4 8% 42%	1748
	21st to end	Day	18% 8% 4 6% 5% 3 3 5% 5% 7% 37%	1480
March	1st to 10th	Day	16% 6% 3 6% 5% 3 4 4 6% 6% 41%	1800
	11th to 20th	Day	15% 7% 4 7% 5% 3 4 4 5% 8% 38%	1980
	21st to end	Day	11% 6% 3 6% 5% 3 5% 4 5% 7% 44%	2326
April	1st to 10th	Day	11% 6% 3 6% 5% 3 5% 5% 6% 7% 43%	2160
	11th to 20th	Day	15% 6% 2 6% 6% 3 5% 4 5% 7% 40%	2134
	21st to end	Day	8% 4 3 5% 5% 4 5% 5% 7% 7% 48%	2160
May	1st to 10th	Day	12% 5% 3 4 5% 4 5% 5% 5% 8% 45%	2160
	11th to 20th	Day	9% 6% 3 7% 7% 4 6% 5% 6% 8% 40%	2124
	21st to end	Day	7% 5% 4 6% 7% 5% 7% 7% 7% 9% 36%	2479
June	1st to 10th	Day	10% 4 2 6% 7% 5% 7% 7% 8% 10% 33%	2340
	11th to 20th	Day	5% 3 3 7% 7% 5% 7% 8% 8% 10% 38%	2444
	21st to end	Day	7% 4 3 7% 8% 5% 8% 9% 9% 11% 29%	2520
July	1st to 10th	Day	7% 6% 4 8% 9% 6% 8% 8% 8% 9% 26%	2342
	11th to 20th	Day	9% 5% 3 7% 9% 5% 8% 9% 8% 10% 27%	2264
	21st to end	Day	9% 6% 3 8% 9% 4 8% 6% 8% 9% 31%	2350
August	1st to 10th	Day	5% 5% 2 7% 7% 5% 7% 7% 8% 12% 34%	2148
	11th to 20th	Day	10% 7% 3 7% 7% 5% 7% 7% 7% 9% 30%	2125
	21st to end	Day	11% 5% 3 7% 7% 4 7% 8% 7% 8% 33%	2376
September	1st to 10th	Day	8% 6% 4 6% 9% 5% 6% 6% 6% 8% 36%	2160
	11th to 20th	Day	10% 7% 2 7% 6% 2 5% 4 6% 8% 41%	2068
	21st to end	Day	11% 4 2 4 4 3 5% 5% 5% 7% 50%	1980
October	1st to 10th	Day	6% 5% 2 4 4 3 4 5% 5% 7% 56%	1969
	11th to 20th	Day	10% 4 2 5% 5% 3 3 4 6% 7% 52%	1800
	21st to end	Day	11% 5% 2 4 4 3 4 4 4 6% 55%	1980
November	1st to 10th	Day	10% 5% 2 5% 4 2 4 3 5% 5% 54%	1820
	11th to 20th	Day	12% 6% 2 4 3 3 3 3 4 6% 54%	1710
	21st to end	Day	14% 6% 2 5% 5% 3 3 5% 4 6% 47%	1710
December	1st to 10th	Day	14% 7% 4 6% 4 2 5% 5% 4 6% 45%	1710
	11th to 20th	Day	15% 9% 3 8% 5% 2 4 4 4 5% 42%	2153
	21st to end	Day	16% 7% 2 5% 5% 3 4 5% 6% 7% 40%	3234
January	1st to 10th	Night	18% 6% 2 4 3 2 3 3 5% 5% 48%	2415
	11th to 20th	Night	16% 7% 3 5% 3 3 4 4 5% 6% 45%	2321
	21st to end	Night	19% 8% 3 5% 4 2 3 3 4 5% 44%	2376
February	1st to 10th	Night	16% 7% 3 5% 5% 2 4 4 5% 7% 41%	2160
	11th to 20th	Night	20% 8% 3 5% 5% 2 3 3 4 5% 43%	2098
	21st to end	Night	18% 8% 4 6% 5% 3 5% 4 4 6% 37%	1776
March	1st to 10th	Night	14% 6% 2 5% 5% 3 3 4 5% 6% 46%	2160
	11th to 20th	Night	13% 6% 3 6% 6% 4 5% 4 5% 7% 41%	1994
	21st to end	Night	12% 5% 2 4 3 2 4 4 4 7% 51%	2030
April	1st to 10th	Night	13% 6% 3 5% 4 3 4 4 5% 7% 46%	1800
	11th to 20th	Night	13% 6% 3 5% 5% 2 4 4 4 8% 46%	1775
	21st to end	Night	7% 4 2 4 4 2 3 4 6% 7% 57%	1800
May	1st to 10th	Night	9% 4 2 4 3 2 3 4 6% 9% 55%	1800
	11th to 20th	Night	6% 5% 2 4 4 4 6% 5% 6% 10% 47%	1769
	21st to end	Night	6% 4 2 4 5% 4 5% 7% 7% 11% 44%	1792
June	1st to 10th	Night	7% 4 3 6% 6% 4 6% 6% 7% 10% 40%	1620
	11th to 20th	Night	3 3 2 5% 5% 3 6% 8% 7% 12% 47%	1508
	21st to end	Night	5% 6% 3 5% 5% 3 5% 6% 8% 13% 40%	1440
July	1st to 10th	Night	5% 6% 3 6% 6% 5% 6% 7% 7% 14% 36%	1610
	11th to 20th	Night	6% 4 2 5% 6% 4 6% 7% 10% 13% 38%	1687
	21st to end	Night	3 3 2 6% 5% 5% 7% 7% 9% 12% 39%	1968
August	1st to 10th	Night	4 2 1 4 5% 4 5% 8% 8% 16% 44%	1790
	11th to 20th	Night	6% 5% 2 6% 5% 4 7% 7% 10% 13% 35%	1776
	21st to end	Night	8% 6% 3 5% 6% 4 6% 6% 7% 11% 38%	1980
September	1st to 10th	Night	8% 5% 3 7% 7% 5% 6% 6% 6% 9% 38%	1800
	11th to 20th	Night	8% 5% 2 5% 6% 4 5% 5% 7% 8% 45%	1872
	21st to end	Night	8% 6% 2 6% 5% 3 4 5% 4 7% 51%	1980
October	1st to 10th	Night	6% 4 2 4 4 2 4 5% 5% 8% 56%	1986
	11th to 20th	Night	8% 4 2 4 4 2 3 4 5% 7% 57%	2160
	21st to end	Night	13% 5% 2 4 4 2 2 4 3 5% 56%	2376
November	1st to 10th	Night	10% 4 1 4 4 2 3 3 5% 5% 60%	2255
	11th to 20th	Night	13% 4 2 3 3 2 3 3 5% 6% 55%	2470
	21st to end	Night	13% 7% 2 4 5% 3 4 5% 5% 5% 47%	2470
December	1st to 10th	Night	15% 7% 2 4 4 3 3 4 5% 6% 46%	2470
	11th to 20th	Night	16% 7% 2 5% 5% 3 5% 4 5% 5% 43%	3042
	21st to end	Night	18% 8% 3 5% 4 3 4 4 4 6% 42%	4404

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	40% 4 6% 18% 22% 9%	1734
	11th to 20th	Day	42% 4 5% 15% 25% 9%	1753
	21st to end	Day	43% 3 4 15% 25% 8%	1980
February	1st to 10th	Day	47% 5% 7% 13% 17% 10%	1800
	11th to 20th	Day	42% 5% 7% 15% 22% 9%	1758
	21st to end	Day	46% 6% 8% 15% 16% 10%	1480
March	1st to 10th	Day	43% 5% 8% 16% 19% 9%	1800
	11th to 20th	Day	44% 7% 9% 14% 19% 8%	1980
	21st to end	Day	39% 6% 10% 17% 22% 7%	2326
April	1st to 10th	Day	39% 7% 9% 17% 19% 9%	2160
	11th to 20th	Day	42% 7% 7% 16% 21% 7%	2134
	21st to end	Day	33% 7% 11% 21% 24% 4	2160
May	1st to 10th	Day	36% 8% 11% 18% 21% 6%	2160
	11th to 20th	Day	40% 8% 12% 20% 18% 2	2128
	21st to end	Day	41% 10% 13% 18% 15% 1	2479
June	1st to 10th	Day	42% 11% 16% 20% 10% 2	2340
	11th to 20th	Day	36% 11% 19% 20% 11% 2	2444
	21st to end	Day	44% 13% 16% 18% 7% 1	2520
July	1st to 10th	Day	50% 15% 17% 14% 5% 1	2278
	11th to 20th	Day	47% 15% 19% 15% 4 1	2195
	21st to end	Day	45% 13% 19% 16% 6% 1	2219
August	1st to 10th	Day	40% 14% 21% 18% 8%	2136
	11th to 20th	Day	47% 14% 16% 14% 8% 2	2125
	21st to end	Day	45% 11% 16% 14% 11% 2	2376
September	1st to 10th	Day	43% 10% 14% 15% 12% 6%	2160
	11th to 20th	Day	40% 9% 12% 16% 16% 7%	2068
	21st to end	Day	33% 7% 12% 20% 19% 9%	1980
October	1st to 10th	Day	28% 5% 12% 18% 25% 12%	1969
	11th to 20th	Day	32% 5% 7% 15% 29% 13%	1800
	21st to end	Day	32% 4 6% 15% 27% 16%	1980
November	1st to 10th	Day	32% 3 8% 17% 26% 13%	1820
	11th to 20th	Day	32% 4 7% 14% 29% 13%	1710
	21st to end	Day	38% 5% 8% 16% 21% 12%	1710
December	1st to 10th	Day	41% 6% 9% 18% 18% 8%	1710
	11th to 20th	Day	45% 5% 7% 12% 23% 8%	2150
	21st to end	Day	40% 7% 9% 19% 20% 4	3234
January	1st to 10th	Night	38% 4 8% 16% 26% 8%	2415
	11th to 20th	Night	41% 5% 7% 17% 21% 9%	2321
	21st to end	Night	44% 3 5% 12% 26% 9%	2376
February	1st to 10th	Night	43% 5% 8% 15% 19% 10%	2160
	11th to 20th	Night	44% 5% 6% 13% 22% 11%	2099
	21st to end	Night	47% 7% 8% 13% 12% 13%	1776
March	1st to 10th	Night	39% 6% 9% 14% 21% 11%	2160
	11th to 20th	Night	43% 7% 11% 14% 19% 7%	1994
	21st to end	Night	33% 6% 12% 19% 23% 7%	2030
April	1st to 10th	Night	38% 6% 10% 16% 20% 10%	1800
	11th to 20th	Night	37% 5% 10% 20% 19% 9%	1775
	21st to end	Night	26% 5% 12% 22% 27% 8%	1800
May	1st to 10th	Night	26% 7% 10% 27% 24% 7%	1800
	11th to 20th	Night	31% 9% 18% 21% 19% 2	1770
	21st to end	Night	29% 12% 18% 21% 17% 3	1793
June	1st to 10th	Night	36% 11% 18% 23% 11% 1	1620
	11th to 20th	Night	25% 13% 20% 28% 10% 2	1508
	21st to end	Night	33% 11% 21% 23% 10% 2	1440
July	1st to 10th	Night	34% 16% 22% 21% 6% 1	1565
	11th to 20th	Night	31% 17% 29% 17% 5% 1	1633
	21st to end	Night	31% 16% 25% 23% 5%	1858
August	1st to 10th	Night	24% 14% 32% 22% 7% 1	1778
	11th to 20th	Night	34% 18% 23% 15% 9% 2	1776
	21st to end	Night	37% 13% 21% 14% 10% 4	1980
September	1st to 10th	Night	39% 10% 18% 13% 14% 6%	1800
	11th to 20th	Night	34% 10% 17% 17% 13% 9%	1872
	21st to end	Night	32% 7% 11% 24% 16% 11%	1980
October	1st to 10th	Night	26% 8% 10% 17% 23% 16%	1986
	11th to 20th	Night	27% 6% 8% 20% 24% 15%	2160
	21st to end	Night	31% 4 7% 14% 25% 18%	2376
November	1st to 10th	Night	27% 4 9% 18% 26% 16%	2255
	11th to 20th	Night	30% 4 8% 15% 28% 15%	2470
	21st to end	Night	37% 5% 7% 19% 19% 13%	2470
December	1st to 10th	Night	38% 5% 9% 20% 20% 7%	2470
	11th to 20th	Night	42% 5% 6% 12% 23% 11%	3044
	21st to end	Night	43% 5% 9% 17% 20% 6%	4404

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% 22% 34% 16% 5% 1	270
	11th to 20th	Day	22% 19% 32% 20% 7% 1	257
	21st to end	Day	24% 27% 32% 14% 4	264
February	1st to 10th	Day	31% 20% 28% 16% 3	240
	11th to 20th	Day	30% 19% 33% 15% 3	240
	21st to end	Day	22% 27% 37% 12% 2	198
March	1st to 10th	Day	21% 18% 37% 20% 4	240
	11th to 20th	Day	26% 23% 27% 20% 4 1	240
	21st to end	Day	18% 16% 30% 26% 9%	412
April	1st to 10th	Day	18% 15% 32% 23% 11% 1	420
	11th to 20th	Day	22% 16% 27% 21% 11% 2	412
	21st to end	Day	10% 14% 29% 29% 17% 2	420
May	1st to 10th	Day	12% 10% 26% 26% 21% 5%	423
	11th to 20th	Day	12% 3 18% 34% 22% 11%	447
	21st to end	Day	7% 3 17% 35% 26% 12%	485
June	1st to 10th	Day	12% 2 16% 30% 25% 15%	450
	11th to 20th	Day	5% 2 11% 34% 35% 12%	554
	21st to end	Day	8% 2 13% 30% 32% 16%	630
July	1st to 10th	Day	7% 2 7% 29% 37% 19%	621
	11th to 20th	Day	8% 1 6% 20% 40% 26%	542
	21st to end	Day	9% 2 5% 22% 37% 25%	488
August	1st to 10th	Day	6% 1 8% 20% 34% 31%	446
	11th to 20th	Day	9% 1 6% 18% 39% 27%	439
	21st to end	Day	11% 2 9% 20% 33% 26%	495
September	1st to 10th	Day	8% 3 8% 27% 36% 17%	450
	11th to 20th	Day	12% 3 9% 25% 38% 12%	450
	21st to end	Day	12% 3 13% 29% 33% 10%	450
October	1st to 10th	Day	5% 5% 21% 36% 24% 8%	439
	11th to 20th	Day	10% 7% 23% 31% 24% 5%	270
	21st to end	Day	20% 11% 19% 30% 14% 5%	297
November	1st to 10th	Day	16% 8% 27% 32% 16% 3	270
	11th to 20th	Day	18% 14% 31% 23% 13% 1	270
	21st to end	Day	15% 16% 34% 22% 11% 2	270
December	1st to 10th	Day	20% 15% 32% 24% 8% 1	270
	11th to 20th	Day	26% 16% 36% 16% 6%	270
	21st to end	Day	27% 17% 27% 23% 6%	297
January	1st to 10th	Night	21% 12% 32% 28% 6%	907
	11th to 20th	Night	20% 13% 31% 29% 7%	833
	21st to end	Night	22% 15% 32% 27% 4	792
February	1st to 10th	Night	20% 13% 33% 29% 4	720
	11th to 20th	Night	24% 16% 28% 27% 6%	703
	21st to end	Night	22% 17% 38% 21% 3	592
March	1st to 10th	Night	17% 16% 33% 28% 7%	720
	11th to 20th	Night	14% 11% 38% 29% 7%	554
	21st to end	Night	14% 11% 36% 30% 9% 1	594
April	1st to 10th	Night	16% 12% 32% 29% 12%	540
	11th to 20th	Night	15% 11% 31% 30% 12% 1	533
	21st to end	Night	9% 5% 30% 41% 16%	540
May	1st to 10th	Night	10% 4 27% 40% 17% 2	540
	11th to 20th	Night	8% 4 22% 40% 22% 4	531
	21st to end	Night	7% 2 17% 35% 32% 7%	584
June	1st to 10th	Night	10% 1 11% 36% 36% 6%	540
	11th to 20th	Night	3 2 9% 33% 44% 10%	540
	21st to end	Night	7% 2 9% 26% 43% 12%	540
July	1st to 10th	Night	4 2 4 23% 52% 15%	525
	11th to 20th	Night	7% 3 18% 49% 23%	522
	21st to end	Night	3 1 6% 25% 48% 18%	591
August	1st to 10th	Night	3 1 3 20% 50% 23%	537
	11th to 20th	Night	7% 1 4 18% 49% 21%	534
	21st to end	Night	9% 2 5% 21% 44% 20%	594
September	1st to 10th	Night	8% 3 8% 27% 40% 14%	540
	11th to 20th	Night	10% 3 9% 28% 42% 8%	612
	21st to end	Night	10% 1 14% 31% 38% 6%	720
October	1st to 10th	Night	8% 2 18% 32% 35% 5%	720
	11th to 20th	Night	10% 4 21% 35% 27% 3	720
	21st to end	Night	15% 7% 21% 31% 23% 2	792
November	1st to 10th	Night	12% 6% 19% 39% 20% 3	740
	11th to 20th	Night	15% 7% 27% 34% 15% 1	760
	21st to end	Night	17% 8% 28% 32% 14% 1	760
December	1st to 10th	Night	18% 13% 28% 28% 13%	760
	11th to 20th	Night	21% 7% 32% 31% 9%	760
	21st to end	Night	25% 12% 28% 28% 6%	836

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