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 2024-11-01.

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	13% 9% 3 8% 5% 5% 5% 4 6% 7% 37%	102030
	Night	12% 9% 3 8% 5% 4 4 4 5% 6% 39%	96999
Transparency	Day	44% 6% 13% 25% 10% 1	101820
	Night	45% 6% 13% 24% 12% 1	96881
Seeing	Day	15% 9% 29% 28% 14% 4	16047
	Night	16% 8% 31% 33% 12% 1	25902

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	13% 14% 5% 14% 7% 5% 5% 3 5% 6% 23%	2527
	11th to 20th	Day	6% 10% 5% 15% 9% 10% 8% 7% 6% 4 21%	2530
	21st to end	Day	7% 19% 8% 12% 5% 5% 5% 4 6% 5% 23%	3107
February	1st to 10th	Day	9% 12% 5% 10% 6% 5% 5% 4 5% 7% 33%	1710
	11th to 20th	Day	7% 12% 4 9% 7% 4 4 4 5% 7% 36%	1664
	21st to end	Day	10% 11% 4 10% 6% 6% 4 3 5% 6% 34%	1462
March	1st to 10th	Day	11% 11% 3 9% 5% 5% 4 3 5% 7% 38%	3344
	11th to 20th	Day	9% 9% 3 9% 5% 4 4 4 5% 8% 39%	3480
	21st to end	Day	20% 12% 4 10% 6% 5% 5% 4 5% 4 25%	3867
April	1st to 10th	Day	16% 12% 3 7% 5% 5% 4 3 5% 6% 34%	2280
	11th to 20th	Day	20% 11% 4 8% 5% 5% 4 2 4 5% 32%	2277
	21st to end	Day	22% 9% 3 8% 5% 4 4 3 5% 5% 32%	2470
May	1st to 10th	Day	17% 7% 2 6% 4 4 4 4 5% 7% 40%	4295
	11th to 20th	Day	14% 7% 2 6% 4 4 4 4 5% 7% 43%	4399
	21st to end	Day	17% 7% 3 7% 5% 5% 4 4 6% 8% 34%	4824
June	1st to 10th	Day	11% 5% 2 6% 4 4 5% 3 6% 8% 45%	2660
	11th to 20th	Day	12% 8% 3 7% 4 5% 5% 5% 6% 8% 39%	2727
	21st to end	Day	10% 4 2 6% 5% 5% 5% 5% 9% 9% 40%	2850
July	1st to 10th	Day	10% 5% 2 6% 5% 5% 6% 6% 7% 10% 38%	4631
	11th to 20th	Day	5% 3 2 4 3 4 3 3 5% 8% 59%	4440
	21st to end	Day	7% 5% 2 5% 3 4 5% 4 6% 10% 50%	4813
August	1st to 10th	Day	12% 6% 2 5% 4 4 4 4 7% 9% 43%	4104
	11th to 20th	Day	12% 5% 2 6% 4 5% 5% 4 7% 9% 42%	4041
	21st to end	Day	11% 6% 2 6% 4 4 5% 4 5% 7% 45%	4347
September	1st to 10th	Day	9% 6% 2 6% 5% 5% 5% 3 7% 7% 47%	2280
	11th to 20th	Day	11% 5% 2 5% 4 5% 5% 4 6% 8% 45%	2256
	21st to end	Day	15% 6% 2 5% 4 3 4 4 5% 7% 44%	1995
October	1st to 10th	Day	17% 7% 3 4 4 4 4 4 6% 7% 40%	1900
	11th to 20th	Day	15% 11% 2 8% 4 4 5% 3 5% 6% 37%	1900
	21st to end	Day	18% 10% 3 7% 5% 4 3 4 4 5% 37%	2048
November	1st to 10th	Day	13% 11% 3 9% 6% 5% 4 4 6% 5% 35%	1541
	11th to 20th	Day	13% 15% 7% 10% 5% 4 4 3 5% 6% 28%	1520
	21st to end	Day	14% 12% 4 8% 5% 4 5% 5% 5% 6% 32%	1520
December	1st to 10th	Day	12% 13% 6% 11% 7% 6% 5% 4 5% 5% 25%	1520
	11th to 20th	Day	11% 15% 7% 10% 6% 6% 4 4 5% 6% 26%	1918
	21st to end	Day	23% 16% 6% 14% 5% 5% 3 3 3 4 18%	2783
January	1st to 10th	Night	12% 12% 6% 14% 6% 4 3 3 4 6% 30%	4428
	11th to 20th	Night	6% 11% 5% 14% 8% 8% 9% 6% 7% 5% 22%	4440
	21st to end	Night	9% 22% 7% 11% 5% 4 4 3 4 5% 25%	4555
February	1st to 10th	Night	6% 11% 5% 9% 6% 5% 5% 4 5% 7% 37%	2470
	11th to 20th	Night	6% 10% 4 8% 6% 5% 6% 4 6% 7% 39%	2403
	21st to end	Night	12% 11% 3 8% 6% 4 6% 3 5% 5% 36%	1990
March	1st to 10th	Night	8% 8% 2 7% 5% 4 4 3 5% 7% 46%	3525
	11th to 20th	Night	9% 9% 3 9% 5% 4 5% 4 6% 6% 40%	3480
	21st to end	Night	25% 11% 4 11% 5% 3 3 2 4 4 29%	3764
April	1st to 10th	Night	16% 11% 3 7% 4 4 4 3 5% 7% 36%	1900
	11th to 20th	Night	21% 10% 3 6% 3 4 4 3 4 5% 38%	1848
	21st to end	Night	20% 10% 3 6% 4 4 3 4 5% 6% 35%	1710
May	1st to 10th	Night	13% 8% 3 8% 5% 4 4 4 5% 6% 41%	2610
	11th to 20th	Night	14% 5% 2 4 3 3 4 2 6% 7% 50%	2506
	21st to end	Night	14% 7% 2 7% 5% 4 4 3 6% 7% 40%	2743
June	1st to 10th	Night	11% 5% 2 5% 5% 4 5% 4 6% 8% 47%	1520
	11th to 20th	Night	9% 5% 2 6% 5% 4 4 4 7% 8% 46%	1444
	21st to end	Night	8% 4 2 6% 4 5% 4 3 6% 9% 49%	1330
July	1st to 10th	Night	10% 4 2 5% 4 4 4 5% 8% 9% 46%	2334
	11th to 20th	Night	4 3 1 4 3 4 4 4 6% 8% 58%	2530
	21st to end	Night	4 4 2 4 4 3 4 4 6% 7% 58%	2750
August	1st to 10th	Night	12% 6% 3 6% 4 3 3 3 5% 7% 48%	2832
	11th to 20th	Night	13% 5% 2 4 3 3 4 3 7% 7% 48%	2798
	21st to end	Night	11% 6% 3 7% 4 4 4 3 5% 7% 45%	3312
September	1st to 10th	Night	8% 4 2 5% 3 4 4 4 5% 8% 53%	1900
	11th to 20th	Night	9% 4 2 5% 4 4 3 3 6% 7% 54%	1922
	21st to end	Night	14% 5% 2 4 3 4 4 3 4 6% 50%	2165
October	1st to 10th	Night	14% 6% 2 5% 3 4 3 4 5% 6% 49%	2280
	11th to 20th	Night	14% 10% 3 6% 4 4 4 4 5% 7% 40%	2280
	21st to end	Night	18% 9% 3 8% 5% 4 3 3 5% 6% 37%	2548
November	1st to 10th	Night	14% 9% 3 7% 4 4 4 4 6% 7% 39%	2539
	11th to 20th	Night	14% 12% 4 11% 6% 5% 4 2 4 5% 33%	2660
	21st to end	Night	13% 9% 3 8% 5% 4 4 4 6% 7% 35%	2660
December	1st to 10th	Night	10% 14% 4 12% 8% 5% 4 4 5% 6% 30%	2660
	11th to 20th	Night	11% 15% 5% 11% 7% 5% 5% 5% 5% 6% 26%	3279
	21st to end	Night	22% 17% 5% 10% 5% 4 3 3 4 4 23%	4884

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	61% 6% 11% 17% 5%	2528
	11th to 20th	Day	62% 5% 13% 15% 5%	2530
	21st to end	Day	59% 7% 13% 15% 5%	3107
February	1st to 10th	Day	50% 6% 12% 22% 8% 1	1710
	11th to 20th	Day	48% 5% 12% 25% 9% 1	1673
	21st to end	Day	51% 5% 11% 21% 11% 1	1462
March	1st to 10th	Day	46% 6% 14% 24% 10% 1	3344
	11th to 20th	Day	42% 4 15% 31% 8%	3480
	21st to end	Day	61% 6% 9% 19% 5%	3867
April	1st to 10th	Day	50% 5% 11% 19% 14% 1	2280
	11th to 20th	Day	54% 5% 9% 18% 12% 2	2277
	21st to end	Day	54% 5% 10% 20% 10%	2470
May	1st to 10th	Day	43% 6% 12% 24% 14% 1	4334
	11th to 20th	Day	39% 6% 12% 28% 13% 2	4403
	21st to end	Day	46% 8% 12% 24% 10% 1	4837
June	1st to 10th	Day	35% 7% 14% 31% 12% 1	2660
	11th to 20th	Day	41% 8% 14% 23% 13% 1	2727
	21st to end	Day	36% 8% 18% 27% 9% 1	2850
July	1st to 10th	Day	38% 7% 18% 24% 13%	4560
	11th to 20th	Day	23% 5% 16% 38% 17% 1	4365
	21st to end	Day	29% 7% 16% 31% 17% 1	4662
August	1st to 10th	Day	35% 7% 13% 31% 12% 2	4090
	11th to 20th	Day	37% 7% 12% 35% 9%	4080
	21st to end	Day	37% 6% 17% 26% 13% 1	4346
September	1st to 10th	Day	34% 7% 15% 33% 11%	2280
	11th to 20th	Day	36% 9% 15% 32% 8%	2256
	21st to end	Day	38% 7% 12% 33% 10% 1	1995
October	1st to 10th	Day	42% 7% 12% 28% 11% 1	1900
	11th to 20th	Day	47% 6% 12% 23% 11% 2	1900
	21st to end	Day	49% 5% 13% 24% 8%	2048
November	1st to 10th	Day	49% 5% 12% 19% 13% 2	1541
	11th to 20th	Day	57% 6% 14% 15% 8%	1520
	21st to end	Day	50% 7% 15% 21% 5% 2	1520
December	1st to 10th	Day	59% 6% 14% 15% 5%	1520
	11th to 20th	Day	58% 6% 15% 16% 4	1915
	21st to end	Day	70% 5% 9% 11% 6%	2783
January	1st to 10th	Night	56% 5% 12% 19% 6% 1	4428
	11th to 20th	Night	60% 6% 12% 15% 6%	4440
	21st to end	Night	61% 5% 9% 19% 5% 1	4555
February	1st to 10th	Night	46% 5% 14% 23% 10% 1	2470
	11th to 20th	Night	43% 7% 15% 25% 10% 1	2404
	21st to end	Night	48% 5% 13% 21% 12% 1	1990
March	1st to 10th	Night	38% 6% 13% 26% 17% 2	3525
	11th to 20th	Night	41% 5% 12% 26% 15% 1	3480
	21st to end	Night	60% 4 8% 19% 8% 1	3764
April	1st to 10th	Night	47% 5% 10% 21% 16% 1	1900
	11th to 20th	Night	49% 5% 8% 21% 15% 2	1848
	21st to end	Night	48% 7% 8% 21% 14% 2	1710
May	1st to 10th	Night	42% 6% 11% 21% 17% 2	2636
	11th to 20th	Night	34% 6% 11% 26% 20% 3	2507
	21st to end	Night	41% 8% 13% 23% 14% 1	2751
June	1st to 10th	Night	33% 8% 15% 28% 14% 2	1520
	11th to 20th	Night	34% 7% 15% 24% 18% 3	1444
	21st to end	Night	28% 9% 14% 31% 14% 3	1330
July	1st to 10th	Night	32% 8% 20% 25% 14% 1	2296
	11th to 20th	Night	22% 6% 13% 38% 19% 2	2482
	21st to end	Night	23% 7% 14% 34% 19% 3	2662
August	1st to 10th	Night	35% 5% 10% 31% 14% 4	2823
	11th to 20th	Night	33% 6% 13% 34% 13% 1	2825
	21st to end	Night	37% 7% 16% 28% 10% 2	3312
September	1st to 10th	Night	28% 6% 15% 34% 16% 1	1900
	11th to 20th	Night	29% 6% 16% 34% 15%	1922
	21st to end	Night	34% 6% 13% 33% 14% 1	2165
October	1st to 10th	Night	36% 4 10% 33% 15% 2	2280
	11th to 20th	Night	43% 5% 13% 24% 13% 1	2280
	21st to end	Night	48% 6% 12% 23% 10% 1	2548
November	1st to 10th	Night	45% 5% 13% 24% 12% 2	2539
	11th to 20th	Night	54% 5% 13% 18% 10% 1	2660
	21st to end	Night	47% 7% 17% 21% 7% 1	2660
December	1st to 10th	Night	55% 6% 14% 19% 5%	2660
	11th to 20th	Night	58% 6% 12% 16% 5% 2	3281
	21st to end	Night	65% 5% 10% 15% 5%	4884

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	13% 10% 30% 31% 11% 4	270
	11th to 20th	Day	14% 8% 38% 33% 7% 1	270
	21st to end	Day	14% 8% 38% 25% 13% 3	297
February	1st to 10th	Day	14% 11% 42% 26% 6% 1	270
	11th to 20th	Day	14% 14% 39% 24% 6% 2	270
	21st to end	Day	17% 11% 38% 29% 4	225
March	1st to 10th	Day	17% 13% 34% 26% 9% 1	270
	11th to 20th	Day	17% 8% 36% 27% 10% 3	270
	21st to end	Day	26% 12% 27% 23% 9% 3	325
April	1st to 10th	Day	22% 15% 32% 25% 7%	460
	11th to 20th	Day	25% 15% 26% 23% 11% 1	475
	21st to end	Day	27% 10% 30% 20% 10% 3	650
May	1st to 10th	Day	19% 12% 32% 26% 10% 2	653
	11th to 20th	Day	18% 10% 29% 28% 12% 3	675
	21st to end	Day	18% 8% 27% 26% 16% 4	734
June	1st to 10th	Day	11% 6% 26% 32% 20% 5%	680
	11th to 20th	Day	13% 7% 35% 31% 12% 2	680
	21st to end	Day	12% 7% 28% 31% 15% 7%	680
July	1st to 10th	Day	9% 4 21% 30% 25% 11%	671
	11th to 20th	Day	7% 5% 25% 31% 20% 11%	668
	21st to end	Day	7% 4 22% 35% 23% 9%	739
August	1st to 10th	Day	11% 3 22% 32% 24% 8%	676
	11th to 20th	Day	14% 4 18% 33% 25% 7%	665
	21st to end	Day	11% 6% 24% 32% 21% 6%	641
September	1st to 10th	Day	12% 5% 29% 30% 20% 4	490
	11th to 20th	Day	12% 6% 26% 30% 21% 5%	466
	21st to end	Day	19% 12% 26% 21% 14% 7%	300
October	1st to 10th	Day	18% 10% 27% 23% 15% 7%	300
	11th to 20th	Day	14% 15% 36% 25% 8% 2	300
	21st to end	Day	21% 13% 42% 15% 7% 2	330
November	1st to 10th	Day	20% 11% 34% 24% 10% 1	270
	11th to 20th	Day	17% 16% 41% 20% 4 1	270
	21st to end	Day	20% 12% 39% 23% 7%	270
December	1st to 10th	Day	14% 9% 41% 23% 12%	270
	11th to 20th	Day	19% 13% 36% 27% 6%	270
	21st to end	Day	28% 11% 34% 24% 3 1	297
January	1st to 10th	Night	13% 9% 35% 32% 9% 1	950
	11th to 20th	Night	15% 7% 37% 31% 8% 1	950
	21st to end	Night	18% 8% 36% 29% 9% 1	1045
February	1st to 10th	Night	11% 9% 39% 31% 10% 1	950
	11th to 20th	Night	10% 10% 41% 29% 8% 1	929
	21st to end	Night	17% 9% 34% 30% 9% 1	734
March	1st to 10th	Night	15% 10% 37% 28% 10%	642
	11th to 20th	Night	16% 10% 37% 30% 6% 1	570
	21st to end	Night	23% 7% 29% 28% 10% 2	627
April	1st to 10th	Night	19% 11% 34% 29% 6%	570
	11th to 20th	Night	26% 8% 32% 26% 7% 1	563
	21st to end	Night	23% 8% 30% 29% 9% 1	570
May	1st to 10th	Night	15% 12% 32% 33% 7%	570
	11th to 20th	Night	16% 8% 30% 34% 11% 1	561
	21st to end	Night	12% 9% 24% 38% 16% 1	617
June	1st to 10th	Night	13% 4 27% 42% 13% 1	570
	11th to 20th	Night	11% 3 30% 44% 11%	570
	21st to end	Night	10% 5% 23% 43% 18% 2	570
July	1st to 10th	Night	7% 1 19% 45% 25% 2	555
	11th to 20th	Night	7% 3 23% 45% 22% 1	552
	21st to end	Night	5% 2 20% 47% 23% 3	624
August	1st to 10th	Night	10% 2 14% 51% 20% 2	567
	11th to 20th	Night	15% 1 18% 35% 27% 3	564
	21st to end	Night	11% 2 22% 39% 24% 2	627
September	1st to 10th	Night	11% 3 22% 43% 18% 3	570
	11th to 20th	Night	9% 5% 30% 35% 20% 2	570
	21st to end	Night	16% 7% 30% 30% 16% 1	645
October	1st to 10th	Night	19% 7% 29% 31% 13% 1	760
	11th to 20th	Night	19% 10% 34% 28% 7% 1	760
	21st to end	Night	22% 9% 32% 30% 7%	836
November	1st to 10th	Night	17% 11% 31% 32% 9%	869
	11th to 20th	Night	19% 11% 35% 27% 8% 1	950
	21st to end	Night	18% 11% 36% 27% 8%	950
December	1st to 10th	Night	15% 9% 34% 33% 8% 1	950
	11th to 20th	Night	18% 9% 37% 27% 8% 1	950
	21st to end	Night	26% 8% 33% 26% 6%	1045

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