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 2026-04-17.

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 7% 5% 5% 5% 4 6% 8% 41%	131373
	Night	13% 6% 2 6% 4 4 4 4 6% 7% 44%	130716
Transparency	Day	38% 8% 12% 17% 17% 7%	135111
	Night	36% 8% 12% 17% 18% 9%	135053
Seeing	Day	14% 9% 21% 25% 22% 10%	16588
	Night	14% 8% 22% 30% 22% 5%	26219

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% 6% 5% 6% 3 3 4 3 5% 6% 42%	5364
	11th to 20th	Day	11% 5% 2 5% 3 4 4 3 4 5% 54%	5575
	21st to end	Day	23% 9% 3 7% 4 3 3 2 4 5% 37%	6436
February	1st to 10th	Day	16% 8% 3 6% 5% 4 5% 3 5% 5% 40%	2100
	11th to 20th	Day	17% 7% 2 6% 5% 4 3 3 4 8% 40%	2048
	21st to end	Day	16% 8% 3 7% 5% 4 3 3 5% 7% 39%	1730
March	1st to 10th	Day	19% 9% 2 7% 5% 5% 5% 4 5% 6% 34%	4580
	11th to 20th	Day	13% 5% 2 7% 4 4 4 3 5% 7% 46%	5090
	21st to end	Day	14% 7% 3 8% 6% 4 4 3 4 5% 40%	5976
April	1st to 10th	Day	12% 7% 2 7% 5% 5% 5% 4 6% 6% 41%	2520
	11th to 20th	Day	14% 6% 2 7% 4 4 5% 3 5% 7% 43%	2446
	21st to end	Day	8% 5% 2 6% 5% 5% 4 4 7% 7% 47%	2400
May	1st to 10th	Day	17% 6% 3 6% 5% 5% 5% 4 6% 9% 34%	5405
	11th to 20th	Day	10% 5% 2 6% 4 5% 6% 4 7% 9% 42%	5404
	21st to end	Day	7% 5% 2 5% 5% 5% 6% 5% 7% 11% 41%	6297
June	1st to 10th	Day	10% 5% 2 7% 6% 6% 6% 6% 8% 10% 34%	2600
	11th to 20th	Day	4 4 2 8% 7% 7% 6% 7% 8% 10% 38%	2716
	21st to end	Day	6% 5% 2 8% 8% 8% 8% 7% 9% 10% 30%	2800
July	1st to 10th	Day	5% 5% 2 8% 7% 8% 7% 6% 8% 12% 30%	5902
	11th to 20th	Day	6% 4 2 7% 6% 7% 8% 6% 9% 12% 33%	5698
	21st to end	Day	7% 6% 3 9% 7% 7% 7% 6% 9% 12% 28%	5922
August	1st to 10th	Day	3 3 1 5% 4 5% 5% 4 6% 10% 56%	3905
	11th to 20th	Day	6% 4 2 6% 5% 6% 6% 5% 7% 11% 43%	3849
	21st to end	Day	8% 5% 3 8% 6% 6% 6% 5% 7% 8% 38%	4312
September	1st to 10th	Day	9% 6% 3 7% 7% 6% 6% 5% 6% 8% 37%	2400
	11th to 20th	Day	10% 7% 2 7% 5% 4 5% 4 6% 7% 42%	2297
	21st to end	Day	10% 4 2 5% 3 4 4 3 5% 7% 52%	2200
October	1st to 10th	Day	7% 5% 2 5% 3 4 4 4 5% 7% 56%	2187
	11th to 20th	Day	9% 4 2 5% 4 3 3 3 5% 6% 56%	2000
	21st to end	Day	10% 5% 2 5% 3 4 3 3 3 6% 56%	2200
November	1st to 10th	Day	11% 5% 2 6% 4 3 3 3 5% 6% 53%	2016
	11th to 20th	Day	11% 6% 2 4 3 4 3 3 4 6% 55%	1890
	21st to end	Day	14% 7% 2 6% 4 3 4 4 4 6% 47%	1890
December	1st to 10th	Day	17% 7% 3 6% 4 3 3 3 4 6% 44%	3020
	11th to 20th	Day	11% 8% 3 7% 5% 4 5% 3 4 5% 46%	3463
	21st to end	Day	17% 7% 2 6% 3 3 4 3 5% 6% 44%	4735
January	1st to 10th	Night	19% 8% 4 6% 3 3 3 3 4 4 43%	7498
	11th to 20th	Night	16% 7% 3 5% 2 3 3 3 4 5% 49%	7346
	21st to end	Night	24% 9% 3 7% 4 3 3 3 3 4 36%	7745
February	1st to 10th	Night	15% 8% 2 6% 4 3 4 3 5% 7% 43%	2520
	11th to 20th	Night	21% 9% 2 6% 4 3 3 3 4 5% 40%	2458
	21st to end	Night	17% 8% 3 7% 4 4 4 3 4 6% 40%	2076
March	1st to 10th	Night	20% 10% 2 6% 4 4 4 3 5% 6% 36%	5493
	11th to 20th	Night	13% 6% 2 6% 4 4 4 3 4 6% 49%	5119
	21st to end	Night	16% 6% 2 6% 4 4 4 4 5% 6% 45%	5195
April	1st to 10th	Night	15% 7% 2 6% 4 4 4 3 5% 6% 45%	2100
	11th to 20th	Night	13% 6% 2 6% 4 3 4 3 4 8% 47%	2035
	21st to end	Night	7% 4 2 5% 3 3 4 4 6% 7% 55%	2000
May	1st to 10th	Night	16% 7% 2 7% 4 4 4 3 6% 8% 39%	4490
	11th to 20th	Night	12% 6% 2 6% 4 5% 4 3 6% 9% 43%	4489
	21st to end	Night	7% 5% 2 6% 5% 6% 6% 5% 8% 11% 40%	4539
June	1st to 10th	Night	7% 5% 3 7% 6% 5% 5% 6% 8% 9% 40%	1800
	11th to 20th	Night	3 4 2 6% 5% 4 6% 6% 8% 11% 45%	1674
	21st to end	Night	5% 7% 2 6% 5% 4 5% 5% 8% 13% 39%	1600
July	1st to 10th	Night	5% 5% 2 7% 5% 6% 7% 5% 9% 12% 37%	4068
	11th to 20th	Night	5% 4 2 7% 6% 6% 6% 6% 10% 12% 36%	4248
	21st to end	Night	6% 6% 3 9% 6% 6% 7% 6% 9% 12% 31%	4929
August	1st to 10th	Night	3 2 1 3 3 4 4 4 7% 13% 56%	3244
	11th to 20th	Night	4 3 1 6% 4 5% 7% 5% 9% 12% 44%	3200
	21st to end	Night	6% 5% 3 7% 5% 5% 6% 5% 8% 10% 40%	3586
September	1st to 10th	Night	9% 5% 2 8% 7% 6% 6% 5% 6% 9% 38%	2000
	11th to 20th	Night	9% 6% 2 6% 5% 5% 4 4 7% 8% 45%	2080
	21st to end	Night	7% 5% 2 6% 4 4 4 4 4 7% 52%	2200
October	1st to 10th	Night	7% 4 2 5% 4 3 4 3 5% 8% 55%	2208
	11th to 20th	Night	8% 4 2 5% 3 2 3 3 5% 6% 60%	2400
	21st to end	Night	12% 5% 2 5% 3 3 2 3 3 5% 57%	2640
November	1st to 10th	Night	10% 5% 1 5% 3 3 2 3 4 4 58%	2499
	11th to 20th	Night	13% 4 1 4 3 3 3 2 5% 5% 56%	2730
	21st to end	Night	12% 7% 2 5% 4 4 4 4 5% 6% 48%	2730
December	1st to 10th	Night	16% 8% 2 5% 4 3 4 3 5% 5% 45%	4380
	11th to 20th	Night	14% 7% 2 6% 4 4 4 3 5% 5% 45%	4952
	21st to end	Night	21% 7% 2 5% 3 3 3 2 3 5% 46%	6445

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% 5% 8% 20% 22% 4	5365
	11th to 20th	Day	32% 4 6% 17% 32% 9%	5575
	21st to end	Day	52% 3 5% 10% 16% 13%	6436
February	1st to 10th	Day	45% 5% 7% 13% 20% 10%	2100
	11th to 20th	Day	42% 6% 7% 15% 21% 9%	2058
	21st to end	Day	45% 5% 7% 15% 17% 10%	1730
March	1st to 10th	Day	48% 6% 8% 13% 17% 8%	4580
	11th to 20th	Day	35% 6% 7% 15% 18% 18%	5090
	21st to end	Day	44% 6% 10% 14% 18% 8%	5978
April	1st to 10th	Day	40% 8% 8% 17% 18% 9%	2520
	11th to 20th	Day	39% 7% 7% 17% 22% 8%	2446
	21st to end	Day	34% 7% 11% 21% 22% 5%	2400
May	1st to 10th	Day	41% 11% 14% 20% 12% 3	5440
	11th to 20th	Day	35% 9% 17% 21% 17% 2	5408
	21st to end	Day	33% 10% 15% 27% 13% 3	6311
June	1st to 10th	Day	40% 11% 17% 20% 10% 2	2600
	11th to 20th	Day	37% 11% 19% 19% 12% 2	2716
	21st to end	Day	42% 13% 17% 19% 7% 1	2800
July	1st to 10th	Day	41% 15% 21% 18% 5%	5838
	11th to 20th	Day	38% 16% 30% 14% 1	5629
	21st to end	Day	43% 14% 19% 19% 3	5752
August	1st to 10th	Day	23% 9% 14% 27% 25% 1	3893
	11th to 20th	Day	32% 11% 17% 26% 13% 1	3885
	21st to end	Day	41% 11% 15% 15% 15% 2	4311
September	1st to 10th	Day	42% 10% 14% 15% 12% 6%	2400
	11th to 20th	Day	39% 9% 11% 17% 17% 7%	2297
	21st to end	Day	31% 6% 13% 21% 19% 10%	2200
October	1st to 10th	Day	25% 4 8% 11% 24% 28%	3564
	11th to 20th	Day	18% 3 6% 14% 28% 31%	3240
	21st to end	Day	22% 3 5% 13% 36% 21%	3538
November	1st to 10th	Day	32% 4 8% 17% 26% 13%	2016
	11th to 20th	Day	31% 4 7% 14% 30% 13%	1890
	21st to end	Day	37% 5% 9% 16% 22% 11%	1890
December	1st to 10th	Day	42% 4 7% 16% 23% 7%	3020
	11th to 20th	Day	39% 6% 9% 14% 21% 10%	3460
	21st to end	Day	40% 6% 7% 19% 25% 4	4735
January	1st to 10th	Night	43% 5% 9% 16% 22% 5%	7499
	11th to 20th	Night	38% 4 5% 17% 25% 12%	7346
	21st to end	Night	52% 4 4 12% 19% 9%	7745
February	1st to 10th	Night	41% 6% 7% 15% 21% 10%	2520
	11th to 20th	Night	47% 5% 6% 12% 20% 10%	2459
	21st to end	Night	44% 7% 8% 14% 14% 13%	2076
March	1st to 10th	Night	46% 6% 9% 11% 20% 8%	5493
	11th to 20th	Night	36% 7% 8% 15% 20% 15%	5119
	21st to end	Night	38% 6% 11% 18% 17% 9%	5195
April	1st to 10th	Night	40% 6% 10% 15% 18% 10%	2100
	11th to 20th	Night	36% 5% 10% 20% 20% 9%	2035
	21st to end	Night	27% 6% 12% 22% 25% 7%	2000
May	1st to 10th	Night	41% 10% 14% 18% 15% 3	4520
	11th to 20th	Night	36% 9% 19% 22% 14% 1	4490
	21st to end	Night	32% 11% 21% 24% 12% 2	4547
June	1st to 10th	Night	35% 11% 18% 22% 12% 2	1800
	11th to 20th	Night	26% 14% 21% 26% 10% 2	1674
	21st to end	Night	33% 11% 21% 23% 9% 2	1600
July	1st to 10th	Night	35% 16% 26% 17% 5% 1	4025
	11th to 20th	Night	35% 18% 33% 13% 2	4197
	21st to end	Night	41% 17% 18% 21% 3	4785
August	1st to 10th	Night	18% 10% 21% 29% 21% 1	3232
	11th to 20th	Night	26% 15% 22% 26% 10% 1	3230
	21st to end	Night	37% 13% 16% 18% 12% 4	3586
September	1st to 10th	Night	39% 10% 18% 14% 13% 6%	2000
	11th to 20th	Night	34% 10% 16% 17% 15% 8%	2080
	21st to end	Night	31% 7% 11% 24% 17% 11%	2200
October	1st to 10th	Night	27% 6% 7% 12% 23% 25%	3611
	11th to 20th	Night	17% 4 5% 19% 21% 34%	3899
	21st to end	Night	21% 4 5% 12% 36% 23%	4252
November	1st to 10th	Night	28% 4 9% 17% 26% 16%	2499
	11th to 20th	Night	30% 4 8% 15% 27% 16%	2730
	21st to end	Night	36% 5% 7% 19% 19% 13%	2730
December	1st to 10th	Night	41% 4 7% 17% 25% 7%	4380
	11th to 20th	Night	39% 6% 8% 16% 22% 9%	4954
	21st to end	Night	42% 4 7% 17% 24% 6%	6445

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% 4 1	330
	11th to 20th	Day	20% 21% 35% 18% 7% 1	330
	21st to end	Day	26% 25% 33% 14% 3	363
February	1st to 10th	Day	25% 20% 33% 17% 5% 1	330
	11th to 20th	Day	28% 20% 34% 14% 3	330
	21st to end	Day	23% 26% 36% 12% 3	273
March	1st to 10th	Day	22% 17% 36% 20% 5%	330
	11th to 20th	Day	25% 21% 28% 20% 4 1	330
	21st to end	Day	18% 15% 30% 27% 9%	536
April	1st to 10th	Day	19% 16% 33% 22% 9% 1	540
	11th to 20th	Day	20% 17% 29% 21% 12% 2	516
	21st to end	Day	9% 14% 27% 27% 18% 3	500
May	1st to 10th	Day	14% 11% 27% 24% 19% 5%	503
	11th to 20th	Day	12% 5% 22% 33% 19% 9%	527
	21st to end	Day	6% 4 20% 36% 24% 11%	573
June	1st to 10th	Day	11% 3 18% 31% 24% 14%	530
	11th to 20th	Day	5% 3 11% 35% 34% 12%	646
	21st to end	Day	7% 2 12% 30% 32% 17%	730
July	1st to 10th	Day	6% 2 8% 29% 37% 19%	721
	11th to 20th	Day	7% 1 6% 19% 40% 27%	633
	21st to end	Day	9% 2 5% 22% 38% 23%	576
August	1st to 10th	Day	5% 1 8% 24% 35% 28%	526
	11th to 20th	Day	8% 1 7% 18% 39% 27%	519
	21st to end	Day	10% 2 9% 21% 34% 23%	583
September	1st to 10th	Day	10% 3 8% 30% 35% 15%	530
	11th to 20th	Day	12% 3 10% 24% 38% 13%	530
	21st to end	Day	11% 4 15% 28% 32% 10%	530
October	1st to 10th	Day	7% 6% 22% 36% 23% 7%	517
	11th to 20th	Day	9% 7% 25% 32% 23% 4	330
	21st to end	Day	18% 10% 21% 29% 17% 5%	363
November	1st to 10th	Day	16% 8% 27% 31% 15% 2	330
	11th to 20th	Day	16% 13% 31% 23% 15% 1	330
	21st to end	Day	14% 17% 36% 20% 10% 2	330
December	1st to 10th	Day	23% 15% 33% 22% 7% 1	330
	11th to 20th	Day	22% 16% 37% 18% 7%	330
	21st to end	Day	26% 17% 27% 23% 8% 1	363
January	1st to 10th	Night	21% 13% 33% 28% 5%	1003
	11th to 20th	Night	20% 15% 31% 28% 7%	937
	21st to end	Night	23% 15% 32% 26% 4	924
February	1st to 10th	Night	19% 13% 35% 28% 5%	840
	11th to 20th	Night	25% 17% 27% 25% 5%	823
	21st to end	Night	20% 19% 37% 21% 3	692
March	1st to 10th	Night	17% 17% 32% 28% 6%	840
	11th to 20th	Night	15% 11% 37% 30% 7%	646
	21st to end	Night	14% 11% 35% 32% 8%	693
April	1st to 10th	Night	18% 12% 31% 28% 11%	630
	11th to 20th	Night	14% 10% 33% 30% 12%	611
	21st to end	Night	9% 6% 29% 40% 16%	600
May	1st to 10th	Night	11% 5% 27% 39% 16% 2	600
	11th to 20th	Night	9% 5% 24% 37% 21% 4	591
	21st to end	Night	7% 3 19% 36% 30% 6%	650
June	1st to 10th	Night	10% 2 11% 37% 35% 5%	600
	11th to 20th	Night	3 3 9% 33% 44% 10%	600
	21st to end	Night	7% 3 10% 25% 44% 12%	600
July	1st to 10th	Night	4 2 4 23% 52% 15%	585
	11th to 20th	Night	6% 1 3 17% 50% 24%	582
	21st to end	Night	4 1 6% 25% 48% 16%	657
August	1st to 10th	Night	3 1 4 20% 51% 22%	597
	11th to 20th	Night	7% 1 5% 18% 49% 21%	594
	21st to end	Night	8% 2 5% 22% 43% 19%	660
September	1st to 10th	Night	9% 3 9% 27% 39% 12%	600
	11th to 20th	Night	10% 3 9% 29% 41% 8%	680
	21st to end	Night	9% 3 15% 31% 36% 6%	800
October	1st to 10th	Night	8% 3 19% 33% 33% 4	800
	11th to 20th	Night	9% 4 21% 36% 27% 3	800
	21st to end	Night	14% 8% 20% 33% 22% 2	880
November	1st to 10th	Night	13% 6% 20% 38% 20% 3	820
	11th to 20th	Night	15% 8% 26% 35% 15% 1	840
	21st to end	Night	16% 9% 28% 32% 14% 1	840
December	1st to 10th	Night	19% 13% 28% 28% 12%	840
	11th to 20th	Night	21% 7% 31% 31% 9%	840
	21st to end	Night	25% 13% 27% 28% 7%	924

Page generated at 2026-04-14 01:44:23. Version ac07

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