Anoka-Ramsey Community College (Cambridge)
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Anoka-Ramsey Community College (Cambridge) clear sky chart from 2005-11-06 to 2026-09-14.

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% 8% 3 8% 5% 4 4 4 6% 7% 39%	150614
	Night	11% 9% 3 8% 5% 4 5% 4 5% 7% 38%	140824
Transparency	Day	43% 5% 13% 26% 12% 1	154164
	Night	44% 5% 12% 24% 13% 1	145354
Seeing	Day	16% 9% 30% 27% 14% 4	18691
	Night	16% 8% 32% 33% 11% 1	28456

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	9% 12% 6% 18% 8% 6% 5% 3 4 5% 23%	4691
	11th to 20th	Day	5% 11% 6% 14% 7% 7% 7% 7% 7% 5% 22%	4710
	21st to end	Day	4 12% 6% 11% 5% 5% 7% 4 7% 7% 33%	5770
February	1st to 10th	Day	9% 12% 4 10% 6% 6% 5% 4 5% 8% 31%	1890
	11th to 20th	Day	7% 11% 4 10% 7% 5% 4 4 5% 7% 36%	1844
	21st to end	Day	9% 11% 4 10% 6% 6% 4 4 5% 6% 35%	1612
March	1st to 10th	Day	11% 9% 2 7% 4 4 4 3 5% 8% 43%	4909
	11th to 20th	Day	10% 10% 3 8% 5% 4 5% 4 5% 8% 39%	5090
	21st to end	Day	19% 11% 4 9% 5% 5% 5% 4 5% 5% 28%	5665
April	1st to 10th	Day	16% 12% 3 7% 5% 5% 4 3 5% 6% 33%	2520
	11th to 20th	Day	19% 11% 4 8% 5% 5% 4 3 4 5% 31%	2520
	21st to end	Day	22% 9% 3 8% 5% 4 4 3 5% 5% 33%	2730
May	1st to 10th	Day	11% 6% 2 6% 4 5% 4 3 5% 6% 49%	8010
	11th to 20th	Day	15% 8% 3 6% 4 4 4 3 5% 6% 44%	8222
	21st to end	Day	14% 7% 2 7% 5% 5% 4 4 6% 8% 39%	9047
June	1st to 10th	Day	11% 6% 2 6% 5% 4 4 4 6% 9% 44%	2940
	11th to 20th	Day	13% 8% 3 7% 4 5% 5% 5% 6% 8% 37%	3015
	21st to end	Day	11% 4 2 5% 5% 5% 5% 5% 9% 10% 39%	3150
July	1st to 10th	Day	10% 5% 2 6% 4 5% 5% 5% 7% 10% 41%	8627
	11th to 20th	Day	7% 3 1 4 3 3 3 3 6% 10% 56%	8280
	21st to end	Day	7% 5% 2 5% 4 4 4 3 6% 10% 49%	8990
August	1st to 10th	Day	9% 5% 2 5% 4 4 5% 4 6% 9% 48%	6014
	11th to 20th	Day	12% 5% 2 6% 4 4 5% 4 7% 10% 39%	5948
	21st to end	Day	10% 6% 2 7% 4 4 5% 4 6% 8% 45%	6318
September	1st to 10th	Day	9% 6% 2 6% 5% 5% 5% 3 7% 8% 45%	2520
	11th to 20th	Day	12% 6% 2 6% 4 5% 5% 4 6% 8% 44%	2411
	21st to end	Day	14% 6% 2 5% 4 3 4 4 5% 7% 45%	2100
October	1st to 10th	Day	16% 7% 2 4 4 4 4 4 6% 8% 41%	2000
	11th to 20th	Day	15% 11% 2 7% 5% 4 4 3 4 6% 37%	2000
	21st to end	Day	18% 11% 3 8% 5% 3 3 3 5% 5% 36%	2156
November	1st to 10th	Day	13% 10% 3 10% 6% 5% 4 4 6% 5% 34%	1707
	11th to 20th	Day	12% 16% 6% 10% 5% 4 4 3 5% 6% 29%	1680
	21st to end	Day	14% 12% 4 9% 5% 4 5% 4 5% 6% 31%	1680
December	1st to 10th	Day	8% 11% 5% 15% 12% 8% 5% 4 5% 5% 21%	2690
	11th to 20th	Day	11% 17% 6% 10% 5% 5% 4 3 5% 6% 28%	3088
	21st to end	Day	20% 18% 8% 19% 6% 4 3 3 3 4 14%	4070
January	1st to 10th	Night	9% 12% 5% 14% 8% 5% 4 3 4 6% 30%	8232
	11th to 20th	Night	5% 12% 5% 13% 7% 7% 10% 7% 7% 6% 23%	8280
	21st to end	Night	6% 14% 5% 8% 5% 5% 5% 4 6% 6% 36%	8425
February	1st to 10th	Night	7% 12% 5% 9% 6% 5% 5% 3 5% 7% 36%	2730
	11th to 20th	Night	6% 10% 4 9% 6% 5% 6% 4 6% 7% 39%	2663
	21st to end	Night	11% 10% 3 8% 7% 4 6% 3 4 6% 36%	2192
March	1st to 10th	Night	10% 7% 2 6% 4 4 4 3 4 7% 48%	5195
	11th to 20th	Night	10% 8% 3 8% 5% 4 5% 5% 8% 9% 36%	5090
	21st to end	Night	23% 11% 4 10% 4 4 3 3 5% 5% 29%	5506
April	1st to 10th	Night	16% 11% 3 7% 4 4 4 3 5% 6% 36%	2100
	11th to 20th	Night	20% 9% 3 6% 3 4 4 3 4 5% 38%	2045
	21st to end	Night	20% 10% 3 6% 4 4 3 4 5% 5% 35%	1890
May	1st to 10th	Night	9% 6% 2 6% 4 4 4 4 5% 7% 49%	4859
	11th to 20th	Night	15% 7% 2 5% 3 3 3 2 5% 6% 49%	4670
	21st to end	Night	14% 7% 3 6% 5% 5% 5% 4 6% 8% 39%	5139
June	1st to 10th	Night	11% 5% 2 5% 5% 4 5% 4 6% 8% 46%	1680
	11th to 20th	Night	10% 5% 2 6% 5% 4 5% 4 6% 8% 45%	1596
	21st to end	Night	9% 4 2 6% 4 4 4 4 6% 9% 48%	1470
July	1st to 10th	Night	9% 4 2 5% 4 4 4 4 7% 10% 46%	4343
	11th to 20th	Night	5% 3 1 5% 3 3 4 4 6% 9% 56%	4707
	21st to end	Night	8% 5% 2 5% 4 4 4 4 6% 7% 50%	5117
August	1st to 10th	Night	10% 5% 2 6% 4 3 3 3 5% 7% 52%	4152
	11th to 20th	Night	13% 6% 3 5% 4 4 4 4 7% 8% 44%	4118
	21st to end	Night	9% 5% 3 6% 4 4 4 3 6% 9% 48%	4816
September	1st to 10th	Night	9% 4 2 6% 3 4 4 3 5% 8% 52%	2100
	11th to 20th	Night	9% 4 2 5% 4 4 3 3 6% 7% 53%	2053
	21st to end	Night	14% 5% 2 4 3 4 4 3 4 6% 51%	2279
October	1st to 10th	Night	14% 6% 2 5% 3 4 3 4 4 6% 49%	2400
	11th to 20th	Night	15% 10% 3 6% 4 4 4 4 5% 7% 39%	2400
	21st to end	Night	18% 9% 3 8% 5% 4 3 3 5% 6% 37%	2682
November	1st to 10th	Night	14% 9% 3 7% 5% 4 4 4 6% 7% 38%	2806
	11th to 20th	Night	14% 12% 4 11% 5% 4 4 2 4 5% 34%	2940
	21st to end	Night	13% 10% 3 9% 5% 4 4 4 6% 7% 34%	2940
December	1st to 10th	Night	7% 10% 4 15% 8% 7% 5% 4 6% 7% 27%	4720
	11th to 20th	Night	10% 16% 6% 14% 6% 5% 5% 6% 5% 5% 23%	5339
	21st to end	Night	21% 18% 8% 15% 5% 4 3 3 3 4 18%	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	63% 4 9% 15% 8%	4692
	11th to 20th	Day	59% 4 11% 17% 9%	4710
	21st to end	Day	48% 5% 14% 23% 10%	5770
February	1st to 10th	Day	51% 6% 12% 22% 8% 1	1890
	11th to 20th	Day	47% 5% 12% 26% 9% 1	1853
	21st to end	Day	50% 5% 12% 22% 10% 1	1612
March	1st to 10th	Day	40% 5% 18% 25% 10% 3	4909
	11th to 20th	Day	43% 3 16% 28% 9% 1	5090
	21st to end	Day	57% 5% 10% 20% 8% 1	5667
April	1st to 10th	Day	51% 5% 10% 19% 14% 1	2520
	11th to 20th	Day	54% 5% 10% 18% 12% 2	2520
	21st to end	Day	54% 5% 10% 21% 10%	2730
May	1st to 10th	Day	35% 4 11% 29% 20% 1	8049
	11th to 20th	Day	41% 4 8% 25% 17% 5%	8226
	21st to end	Day	42% 5% 9% 30% 12% 1	9061
June	1st to 10th	Day	35% 7% 14% 31% 11% 1	2940
	11th to 20th	Day	42% 8% 14% 23% 13% 1	3015
	21st to end	Day	37% 8% 17% 28% 9% 1	3150
July	1st to 10th	Day	36% 6% 17% 32% 8%	8556
	11th to 20th	Day	24% 4 15% 39% 17% 1	8205
	21st to end	Day	30% 5% 15% 33% 17%	8794
August	1st to 10th	Day	32% 6% 14% 34% 13% 1	6000
	11th to 20th	Day	38% 6% 18% 30% 7%	5987
	21st to end	Day	35% 5% 17% 29% 12% 1	6317
September	1st to 10th	Day	34% 7% 15% 33% 11%	2520
	11th to 20th	Day	36% 9% 16% 31% 7%	2411
	21st to end	Day	38% 7% 11% 33% 11% 1	2100
October	1st to 10th	Day	31% 4 11% 34% 19% 1	3260
	11th to 20th	Day	41% 4 11% 28% 15% 2	3240
	21st to end	Day	46% 4 16% 26% 8%	3458
November	1st to 10th	Day	50% 5% 12% 19% 12% 1	1707
	11th to 20th	Day	55% 6% 14% 17% 8%	1680
	21st to end	Day	51% 7% 14% 20% 6% 2	1680
December	1st to 10th	Day	64% 6% 12% 13% 4 1	2690
	11th to 20th	Day	57% 5% 11% 20% 7%	3085
	21st to end	Day	76% 4 7% 8% 5%	4070
January	1st to 10th	Night	56% 4 14% 16% 9%	8233
	11th to 20th	Night	59% 5% 9% 16% 10%	8280
	21st to end	Night	47% 5% 12% 26% 10%	8425
February	1st to 10th	Night	48% 5% 14% 22% 10% 1	2730
	11th to 20th	Night	43% 6% 14% 25% 10% 1	2664
	21st to end	Night	48% 4 13% 22% 11% 1	2192
March	1st to 10th	Night	37% 4 14% 23% 17% 4	5195
	11th to 20th	Night	41% 5% 16% 24% 14%	5090
	21st to end	Night	59% 3 10% 16% 11% 1	5506
April	1st to 10th	Night	47% 5% 10% 22% 16% 1	2100
	11th to 20th	Night	48% 4 9% 22% 15% 2	2045
	21st to end	Night	49% 7% 8% 21% 14% 2	1890
May	1st to 10th	Night	33% 5% 10% 31% 20% 2	4885
	11th to 20th	Night	37% 4 9% 21% 21% 8%	4671
	21st to end	Night	43% 6% 9% 28% 13% 1	5149
June	1st to 10th	Night	34% 8% 14% 28% 14% 2	1680
	11th to 20th	Night	35% 6% 15% 24% 17% 3	1596
	21st to end	Night	30% 9% 14% 31% 14% 3	1470
July	1st to 10th	Night	32% 7% 18% 30% 13% 1	4307
	11th to 20th	Night	24% 5% 13% 38% 19% 2	4662
	21st to end	Night	32% 6% 13% 33% 15% 1	5002
August	1st to 10th	Night	32% 5% 12% 34% 15% 3	4143
	11th to 20th	Night	37% 6% 15% 30% 11% 1	4145
	21st to end	Night	33% 6% 17% 32% 10% 1	4816
September	1st to 10th	Night	29% 6% 15% 34% 16% 1	2100
	11th to 20th	Night	29% 6% 18% 33% 14%	2053
	21st to end	Night	33% 5% 12% 34% 14% 1	2279
October	1st to 10th	Night	24% 3 7% 36% 25% 4	3920
	11th to 20th	Night	35% 4 12% 26% 21% 2	3899
	21st to end	Night	44% 4 12% 27% 12%	4330
November	1st to 10th	Night	45% 5% 13% 24% 11% 2	2806
	11th to 20th	Night	53% 5% 13% 19% 10% 1	2940
	21st to end	Night	49% 7% 16% 21% 6% 1	2940
December	1st to 10th	Night	56% 6% 15% 19% 4	4720
	11th to 20th	Night	62% 5% 10% 17% 6% 1	5341
	21st to end	Night	71% 4 8% 13% 5%	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	12% 12% 32% 29% 10% 4	330
	11th to 20th	Day	13% 9% 39% 31% 7% 1	330
	21st to end	Day	13% 10% 39% 24% 12% 2	363
February	1st to 10th	Day	14% 13% 42% 24% 5% 1	330
	11th to 20th	Day	13% 12% 39% 26% 8% 2	330
	21st to end	Day	16% 12% 40% 27% 5%	273
March	1st to 10th	Day	18% 13% 37% 25% 7% 1	330
	11th to 20th	Day	19% 9% 36% 25% 9% 2	330
	21st to end	Day	26% 13% 30% 21% 7% 3	394
April	1st to 10th	Day	22% 16% 31% 26% 6%	540
	11th to 20th	Day	24% 16% 28% 21% 10% 1	558
	21st to end	Day	27% 10% 31% 21% 9% 3	750
May	1st to 10th	Day	18% 12% 30% 27% 11% 2	753
	11th to 20th	Day	19% 11% 28% 27% 11% 3	775
	21st to end	Day	19% 8% 27% 27% 15% 4	844
June	1st to 10th	Day	12% 6% 27% 32% 19% 4	780
	11th to 20th	Day	14% 8% 35% 30% 11% 2	780
	21st to end	Day	14% 7% 29% 30% 14% 6%	780
July	1st to 10th	Day	9% 4 20% 30% 26% 11%	771
	11th to 20th	Day	7% 5% 25% 33% 20% 10%	768
	21st to end	Day	7% 4 24% 36% 22% 8%	849
August	1st to 10th	Day	10% 3 22% 32% 24% 8%	776
	11th to 20th	Day	14% 4 19% 33% 24% 6%	765
	21st to end	Day	11% 6% 24% 33% 21% 6%	739
September	1st to 10th	Day	12% 6% 29% 29% 19% 4	570
	11th to 20th	Day	12% 6% 27% 30% 21% 4	517
	21st to end	Day	18% 11% 25% 21% 17% 8%	330
October	1st to 10th	Day	17% 10% 28% 24% 15% 6%	330
	11th to 20th	Day	16% 15% 36% 23% 7% 2	330
	21st to end	Day	21% 13% 40% 17% 7% 2	363
November	1st to 10th	Day	20% 14% 33% 23% 9% 1	330
	11th to 20th	Day	18% 18% 39% 19% 5% 1	330
	21st to end	Day	21% 13% 37% 22% 6%	330
December	1st to 10th	Day	15% 10% 41% 23% 11%	330
	11th to 20th	Day	20% 13% 37% 25% 5%	330
	21st to end	Day	28% 12% 35% 22% 3 1	363
January	1st to 10th	Night	14% 10% 34% 32% 9% 1	1050
	11th to 20th	Night	15% 8% 38% 30% 8% 1	1050
	21st to end	Night	17% 8% 37% 29% 8% 1	1155
February	1st to 10th	Night	12% 10% 40% 29% 9%	1050
	11th to 20th	Night	10% 10% 42% 29% 8% 1	1029
	21st to end	Night	16% 9% 36% 30% 9%	808
March	1st to 10th	Night	15% 10% 37% 28% 9%	710
	11th to 20th	Night	17% 11% 37% 29% 6% 1	630
	21st to end	Night	23% 8% 30% 28% 9% 2	693
April	1st to 10th	Night	19% 13% 33% 29% 6%	630
	11th to 20th	Night	25% 9% 32% 26% 8% 1	623
	21st to end	Night	23% 9% 30% 28% 9% 1	630
May	1st to 10th	Night	15% 12% 32% 32% 9%	630
	11th to 20th	Night	16% 10% 30% 33% 11% 1	621
	21st to end	Night	13% 8% 24% 39% 15% 1	683
June	1st to 10th	Night	14% 4 27% 42% 12% 1	630
	11th to 20th	Night	12% 3 30% 44% 10%	630
	21st to end	Night	10% 6% 23% 43% 17% 2	630
July	1st to 10th	Night	7% 1 19% 47% 24% 2	615
	11th to 20th	Night	7% 3 24% 45% 21% 1	612
	21st to end	Night	6% 2 22% 47% 21% 3	690
August	1st to 10th	Night	10% 3 15% 49% 21% 2	627
	11th to 20th	Night	15% 2 20% 36% 25% 2	624
	21st to end	Night	10% 2 23% 40% 24% 2	693
September	1st to 10th	Night	12% 3 22% 42% 18% 3	630
	11th to 20th	Night	9% 5% 30% 36% 19% 1	609
	21st to end	Night	15% 7% 29% 31% 17% 1	679
October	1st to 10th	Night	18% 8% 29% 31% 13% 1	800
	11th to 20th	Night	20% 10% 35% 28% 7% 1	800
	21st to end	Night	22% 9% 32% 30% 7%	880
November	1st to 10th	Night	17% 11% 32% 31% 8%	960
	11th to 20th	Night	19% 12% 35% 27% 7%	1050
	21st to end	Night	18% 12% 37% 26% 7%	1050
December	1st to 10th	Night	15% 9% 36% 32% 8% 1	1050
	11th to 20th	Night	18% 11% 37% 26% 7% 1	1050
	21st to end	Night	26% 8% 33% 26% 6% 1	1155

Page generated at 2026-09-11 03:11:53. Version ac07

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