IUP Northpointe Regional Campus
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the IUP Northpointe Regional Campus clear sky chart from 2005-11-06 to 2026-01-02.

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	16% 11% 4 9% 5% 5% 4 4 5% 7% 31%	127079
	Night	17% 11% 4 9% 5% 4 4 3 5% 6% 31%	124275
Transparency	Day	51% 6% 11% 20% 10% 1	130680
	Night	52% 6% 11% 19% 11% 1	128743
Seeing	Day	23% 15% 27% 20% 11% 4	16128
	Night	22% 12% 26% 26% 11% 1	25825

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	16% 20% 10% 21% 5% 3 2 2 3 3 16%	3944
	11th to 20th	Day	13% 22% 10% 19% 9% 6% 2 2 2 2 13%	4060
	21st to end	Day	21% 21% 6% 11% 7% 5% 4 3 3 5% 16%	4466
February	1st to 10th	Day	19% 19% 5% 11% 7% 4 3 3 4 4 21%	1800
	11th to 20th	Day	17% 16% 6% 14% 5% 5% 5% 4 4 6% 20%	1753
	21st to end	Day	20% 14% 5% 11% 6% 4 3 3 4 6% 24%	1640
March	1st to 10th	Day	17% 12% 5% 9% 5% 4 4 2 4 5% 33%	4935
	11th to 20th	Day	13% 10% 4 9% 4 5% 5% 4 5% 6% 36%	4980
	21st to end	Day	17% 10% 4 9% 5% 5% 5% 4 5% 6% 31%	5465
April	1st to 10th	Day	17% 12% 4 8% 4 5% 4 3 6% 6% 29%	2329
	11th to 20th	Day	17% 11% 4 7% 6% 4 4 4 5% 6% 32%	2384
	21st to end	Day	22% 9% 3 7% 5% 4 4 3 4 6% 34%	2600
May	1st to 10th	Day	21% 9% 4 8% 5% 5% 5% 3 6% 7% 27%	5862
	11th to 20th	Day	19% 8% 3 7% 5% 5% 5% 4 6% 9% 28%	5861
	21st to end	Day	20% 7% 2 6% 4 5% 5% 4 6% 8% 32%	6934
June	1st to 10th	Day	14% 7% 3 6% 6% 6% 5% 4 7% 8% 34%	2800
	11th to 20th	Day	15% 7% 3 7% 5% 5% 5% 5% 7% 8% 33%	2800
	21st to end	Day	14% 7% 2 6% 5% 5% 4 4 6% 9% 37%	2800
July	1st to 10th	Day	10% 7% 2 6% 5% 6% 5% 4 5% 9% 41%	6323
	11th to 20th	Day	11% 7% 3 8% 6% 5% 5% 4 7% 10% 34%	5900
	21st to end	Day	11% 7% 2 7% 5% 4 5% 4 6% 7% 41%	6424
August	1st to 10th	Day	16% 8% 3 8% 6% 5% 5% 4 7% 7% 30%	4234
	11th to 20th	Day	12% 6% 3 7% 5% 6% 6% 5% 6% 8% 36%	4174
	21st to end	Day	9% 4 2 6% 5% 5% 6% 5% 8% 10% 40%	4421
September	1st to 10th	Day	15% 7% 2 6% 4 3 5% 3 5% 6% 44%	2400
	11th to 20th	Day	11% 6% 2 6% 4 4 5% 4 6% 8% 45%	2242
	21st to end	Day	21% 8% 3 7% 4 5% 4 3 5% 6% 35%	2177
October	1st to 10th	Day	16% 7% 2 7% 4 3 4 4 6% 7% 41%	2000
	11th to 20th	Day	20% 8% 3 6% 5% 5% 4 4 5% 6% 35%	2000
	21st to end	Day	23% 10% 3 7% 4 4 3 3 5% 6% 31%	2200
November	1st to 10th	Day	12% 8% 3 7% 5% 4 4 4 6% 6% 41%	1993
	11th to 20th	Day	19% 14% 4 7% 4 4 4 3 5% 6% 30%	1700
	21st to end	Day	19% 16% 5% 9% 5% 4 4 4 5% 6% 23%	1680
December	1st to 10th	Day	19% 16% 8% 20% 5% 4 3 2 3 4 16%	2680
	11th to 20th	Day	23% 18% 7% 10% 4 3 3 3 3 4 22%	3070
	21st to end	Day	23% 21% 6% 11% 5% 4 3 3 4 5% 16%	4048
January	1st to 10th	Night	15% 17% 8% 23% 5% 3 3 3 3 3 16%	6022
	11th to 20th	Night	14% 17% 9% 18% 9% 6% 4 3 3 4 14%	5900
	21st to end	Night	23% 16% 6% 12% 6% 5% 5% 2 3 3 19%	6490
February	1st to 10th	Night	20% 14% 5% 12% 6% 4 4 3 4 4 23%	2600
	11th to 20th	Night	19% 13% 4 13% 5% 5% 4 3 5% 5% 24%	2533
	21st to end	Night	19% 13% 4 12% 6% 5% 4 3 5% 5% 25%	1986
March	1st to 10th	Night	20% 12% 5% 9% 5% 3 3 3 3 5% 31%	4918
	11th to 20th	Night	14% 10% 5% 6% 4 3 3 3 4 6% 41%	4980
	21st to end	Night	17% 10% 4 8% 5% 4 4 3 4 5% 36%	5467
April	1st to 10th	Night	19% 13% 4 6% 4 4 4 3 3 6% 33%	2070
	11th to 20th	Night	16% 9% 3 7% 4 4 5% 4 5% 7% 36%	1975
	21st to end	Night	15% 9% 3 8% 5% 4 4 3 5% 8% 35%	1806
May	1st to 10th	Night	28% 10% 3 7% 4 4 4 3 5% 6% 26%	4033
	11th to 20th	Night	20% 8% 3 7% 4 4 3 3 5% 7% 35%	4015
	21st to end	Night	20% 6% 3 6% 4 4 4 3 6% 8% 35%	3920
June	1st to 10th	Night	11% 6% 1 7% 5% 3 4 5% 5% 8% 44%	1600
	11th to 20th	Night	12% 6% 3 7% 4 4 5% 4 6% 8% 41%	1600
	21st to end	Night	11% 5% 2 5% 5% 5% 5% 5% 7% 10% 41%	1600
July	1st to 10th	Night	13% 7% 3 8% 5% 4 4 3 5% 8% 42%	3630
	11th to 20th	Night	12% 6% 3 8% 5% 5% 5% 4 8% 9% 36%	4057
	21st to end	Night	10% 7% 3 7% 5% 5% 4 4 6% 8% 43%	4427
August	1st to 10th	Night	15% 7% 3 8% 5% 4 5% 4 6% 7% 37%	2915
	11th to 20th	Night	14% 7% 3 6% 4 5% 4 3 6% 7% 42%	2875
	21st to end	Night	9% 4 2 6% 4 5% 5% 5% 7% 9% 44%	3444
September	1st to 10th	Night	12% 5% 3 5% 4 3 4 4 5% 6% 50%	2000
	11th to 20th	Night	9% 4 2 5% 3 3 4 3 6% 8% 53%	2155
	21st to end	Night	17% 8% 3 7% 4 4 5% 4 5% 6% 38%	2221
October	1st to 10th	Night	14% 6% 2 6% 4 4 4 3 5% 7% 45%	2400
	11th to 20th	Night	18% 7% 2 6% 4 4 4 3 5% 7% 40%	2400
	21st to end	Night	22% 9% 2 6% 4 4 4 3 4 7% 35%	2640
November	1st to 10th	Night	13% 9% 2 6% 4 4 4 4 4 7% 42%	2523
	11th to 20th	Night	18% 12% 4 6% 5% 5% 5% 3 6% 6% 29%	2918
	21st to end	Night	20% 14% 4 7% 5% 4 4 4 4 6% 28%	2940
December	1st to 10th	Night	17% 17% 10% 13% 4 4 4 3 5% 5% 17%	4720
	11th to 20th	Night	22% 16% 6% 11% 4 4 4 3 3 5% 22%	5345
	21st to end	Night	23% 17% 6% 11% 5% 5% 4 3 4 5% 17%	7150

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	75% 4 7% 9% 5%	3945
	11th to 20th	Day	79% 3 5% 8% 3 1	4060
	21st to end	Day	73% 3 9% 10% 5%	4466
February	1st to 10th	Day	68% 4 8% 13% 6%	1800
	11th to 20th	Day	66% 5% 10% 13% 6%	1762
	21st to end	Day	62% 5% 11% 14% 7% 1	1640
March	1st to 10th	Day	53% 6% 11% 22% 8% 1	4935
	11th to 20th	Day	49% 6% 14% 22% 8% 2	4980
	21st to end	Day	53% 5% 9% 20% 12% 1	5465
April	1st to 10th	Day	54% 6% 10% 17% 11% 2	2329
	11th to 20th	Day	52% 6% 10% 18% 13% 2	2384
	21st to end	Day	51% 5% 10% 21% 12% 1	2600
May	1st to 10th	Day	55% 7% 10% 17% 8% 3	5897
	11th to 20th	Day	50% 8% 11% 20% 9% 1	5865
	21st to end	Day	46% 8% 13% 21% 10% 2	6949
June	1st to 10th	Day	45% 8% 13% 21% 11% 1	2800
	11th to 20th	Day	46% 8% 14% 19% 12% 1	2800
	21st to end	Day	42% 8% 12% 25% 11% 1	2800
July	1st to 10th	Day	40% 7% 10% 27% 14% 2	6253
	11th to 20th	Day	43% 7% 13% 26% 11%	5831
	21st to end	Day	39% 7% 11% 23% 19% 1	6240
August	1st to 10th	Day	50% 8% 13% 20% 8%	4221
	11th to 20th	Day	42% 8% 12% 27% 10% 1	4213
	21st to end	Day	36% 9% 13% 28% 13% 2	4421
September	1st to 10th	Day	40% 6% 9% 23% 18% 3	2400
	11th to 20th	Day	36% 6% 15% 26% 15% 1	2242
	21st to end	Day	50% 6% 11% 20% 13% 1	2177
October	1st to 10th	Day	34% 6% 11% 30% 19% 1	3260
	11th to 20th	Day	43% 6% 11% 22% 14% 4	3240
	21st to end	Day	39% 5% 12% 29% 15% 1	3538
November	1st to 10th	Day	43% 6% 12% 20% 17% 2	1993
	11th to 20th	Day	56% 5% 11% 18% 9% 2	1700
	21st to end	Day	62% 6% 11% 15% 5% 1	1680
December	1st to 10th	Day	74% 5% 9% 8% 3	2680
	11th to 20th	Day	67% 3 11% 14% 4	3066
	21st to end	Day	73% 4 9% 10% 4	4048
January	1st to 10th	Night	74% 4 7% 11% 3	6022
	11th to 20th	Night	75% 4 9% 9% 2	5900
	21st to end	Night	72% 4 8% 11% 4 1	6490
February	1st to 10th	Night	65% 4 9% 16% 6%	2600
	11th to 20th	Night	63% 5% 10% 15% 6%	2535
	21st to end	Night	61% 6% 8% 15% 9% 1	1986
March	1st to 10th	Night	57% 4 10% 21% 8%	4918
	11th to 20th	Night	44% 5% 14% 25% 8% 3	4980
	21st to end	Night	49% 5% 11% 18% 16% 1	5467
April	1st to 10th	Night	53% 6% 10% 18% 13% 1	2070
	11th to 20th	Night	47% 7% 12% 17% 15% 3	1975
	21st to end	Night	46% 6% 10% 23% 12% 3	1806
May	1st to 10th	Night	58% 6% 9% 14% 9% 3	4060
	11th to 20th	Night	48% 7% 10% 24% 11% 1	4016
	21st to end	Night	44% 7% 13% 22% 11% 3	3927
June	1st to 10th	Night	37% 8% 13% 24% 15% 2	1600
	11th to 20th	Night	38% 9% 13% 24% 13% 2	1600
	21st to end	Night	37% 9% 14% 22% 17% 1	1600
July	1st to 10th	Night	41% 6% 9% 24% 18% 2	3592
	11th to 20th	Night	41% 8% 17% 22% 11% 1	4006
	21st to end	Night	37% 7% 10% 20% 25% 1	4297
August	1st to 10th	Night	46% 8% 13% 22% 11% 1	2904
	11th to 20th	Night	41% 7% 9% 29% 13% 1	2902
	21st to end	Night	33% 9% 13% 29% 13% 2	3444
September	1st to 10th	Night	33% 7% 12% 22% 20% 4	2000
	11th to 20th	Night	29% 6% 13% 29% 22% 1	2155
	21st to end	Night	47% 5% 11% 20% 15% 1	2221
October	1st to 10th	Night	36% 5% 8% 26% 23% 1	3920
	11th to 20th	Night	37% 5% 12% 23% 16% 7%	3899
	21st to end	Night	36% 4 11% 27% 20% 1	4252
November	1st to 10th	Night	41% 6% 12% 22% 16% 3	2523
	11th to 20th	Night	54% 5% 10% 18% 9% 3	2918
	21st to end	Night	57% 6% 11% 19% 5% 1	2940
December	1st to 10th	Night	70% 5% 12% 11% 3	4720
	11th to 20th	Night	67% 4 12% 14% 3	5348
	21st to end	Night	69% 6% 10% 13% 3	7150

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	33% 28% 22% 12% 4 1	275
	11th to 20th	Day	37% 27% 28% 5% 2 1	300
	21st to end	Day	32% 24% 33% 8% 3	330
February	1st to 10th	Day	34% 28% 31% 5% 2	300
	11th to 20th	Day	42% 25% 26% 6% 1	300
	21st to end	Day	36% 28% 28% 7% 1	299
March	1st to 10th	Day	32% 22% 28% 14% 3	500
	11th to 20th	Day	33% 20% 30% 12% 4 1	500
	21st to end	Day	33% 20% 28% 15% 3 1	550
April	1st to 10th	Day	32% 20% 25% 16% 6% 1	500
	11th to 20th	Day	26% 21% 28% 14% 9% 2	492
	21st to end	Day	28% 20% 27% 17% 5% 2	500
May	1st to 10th	Day	27% 18% 28% 18% 6% 3	503
	11th to 20th	Day	24% 13% 33% 16% 11% 4	527
	21st to end	Day	18% 11% 26% 25% 15% 5%	573
June	1st to 10th	Day	17% 13% 28% 26% 13% 3	530
	11th to 20th	Day	18% 14% 24% 25% 14% 4	530
	21st to end	Day	16% 11% 31% 26% 13% 3	530
July	1st to 10th	Day	13% 8% 20% 29% 20% 10%	525
	11th to 20th	Day	11% 8% 26% 31% 16% 8%	524
	21st to end	Day	13% 5% 26% 31% 18% 7%	576
August	1st to 10th	Day	12% 8% 25% 25% 21% 10%	526
	11th to 20th	Day	14% 7% 22% 28% 18% 11%	519
	21st to end	Day	11% 6% 25% 26% 22% 10%	583
September	1st to 10th	Day	17% 9% 21% 25% 19% 9%	530
	11th to 20th	Day	10% 4 22% 30% 22% 12%	530
	21st to end	Day	26% 12% 21% 24% 13% 4	530
October	1st to 10th	Day	17% 10% 26% 22% 20% 5%	530
	11th to 20th	Day	25% 15% 28% 21% 8% 2	530
	21st to end	Day	30% 16% 29% 17% 8%	583
November	1st to 10th	Day	20% 19% 30% 19% 9% 3	471
	11th to 20th	Day	32% 18% 32% 11% 5% 2	230
	21st to end	Day	29% 21% 39% 10% 1	220
December	1st to 10th	Day	33% 27% 29% 9% 2 1	220
	11th to 20th	Day	36% 22% 28% 11% 2	220
	21st to end	Day	39% 18% 28% 12% 3	242
January	1st to 10th	Night	29% 22% 33% 13% 3	805
	11th to 20th	Night	31% 18% 32% 16% 3	800
	21st to end	Night	31% 19% 31% 17% 3	880
February	1st to 10th	Night	31% 18% 28% 22% 2	800
	11th to 20th	Night	31% 20% 33% 14% 1	783
	21st to end	Night	30% 17% 33% 19% 2	660
March	1st to 10th	Night	26% 18% 33% 21% 2	800
	11th to 20th	Night	28% 19% 26% 21% 6% 1	800
	21st to end	Night	23% 17% 35% 20% 4 1	880
April	1st to 10th	Night	28% 16% 30% 21% 5%	800
	11th to 20th	Night	24% 15% 31% 21% 8% 1	791
	21st to end	Night	20% 11% 32% 31% 6%	606
May	1st to 10th	Night	24% 9% 24% 34% 8% 1	600
	11th to 20th	Night	22% 8% 27% 33% 10%	587
	21st to end	Night	13% 5% 25% 33% 21% 3	433
June	1st to 10th	Night	12% 5% 28% 40% 14% 1	400
	11th to 20th	Night	12% 7% 25% 37% 19% 1	400
	21st to end	Night	10% 4 29% 37% 19% 2	400
July	1st to 10th	Night	11% 3 18% 42% 23% 3	396
	11th to 20th	Night	12% 4 15% 36% 30% 4	582
	21st to end	Night	12% 3 14% 43% 27% 1	657
August	1st to 10th	Night	9% 3 15% 44% 26% 2	597
	11th to 20th	Night	12% 5% 13% 36% 30% 4	594
	21st to end	Night	11% 3 21% 33% 27% 5%	790
September	1st to 10th	Night	14% 5% 20% 34% 24% 3	800
	11th to 20th	Night	10% 4 17% 36% 29% 4	800
	21st to end	Night	20% 9% 22% 28% 19% 3	800
October	1st to 10th	Night	18% 8% 22% 30% 22% 2	800
	11th to 20th	Night	21% 10% 31% 28% 10% 1	800
	21st to end	Night	26% 14% 25% 28% 7%	880
November	1st to 10th	Night	18% 12% 29% 30% 10%	820
	11th to 20th	Night	27% 15% 28% 22% 6% 1	840
	21st to end	Night	30% 14% 31% 19% 6%	840
December	1st to 10th	Night	32% 19% 27% 17% 4	840
	11th to 20th	Night	30% 19% 28% 20% 3	840
	21st to end	Night	30% 18% 28% 21% 2	924

Page generated at 2025-12-30 01:14:05. Version ac07

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