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 2025-05-11.

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	12% 9% 3 8% 5% 5% 4 4 6% 7% 37%	114584
	Night	12% 10% 4 9% 5% 4 4 4 5% 6% 37%	114574
Transparency	Day	45% 6% 13% 25% 11% 1	118178
	Night	45% 5% 12% 23% 12% 1	119123
Seeing	Day	16% 9% 30% 27% 14% 4	16685
	Night	16% 8% 31% 33% 11% 1	26712

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% 5% 16% 8% 5% 5% 3 4 6% 27%	3617
	11th to 20th	Day	5% 10% 6% 14% 7% 8% 7% 8% 8% 5% 21%	3620
	21st to end	Day	5% 16% 7% 13% 5% 5% 5% 3 6% 6% 30%	4460
February	1st to 10th	Day	9% 12% 4 10% 6% 6% 5% 4 5% 7% 32%	1800
	11th to 20th	Day	7% 11% 4 9% 7% 5% 4 4 5% 7% 36%	1754
	21st to end	Day	10% 11% 4 10% 6% 6% 4 4 5% 6% 35%	1537
March	1st to 10th	Day	11% 9% 2 7% 4 4 4 3 5% 8% 43%	4802
	11th to 20th	Day	9% 10% 3 8% 5% 4 5% 4 5% 8% 40%	4980
	21st to end	Day	19% 11% 4 9% 5% 5% 5% 4 5% 5% 28%	5543
April	1st to 10th	Day	16% 12% 3 7% 5% 5% 4 3 5% 6% 34%	2400
	11th to 20th	Day	19% 11% 4 8% 5% 5% 4 2 4 6% 31%	2399
	21st to end	Day	22% 9% 3 8% 5% 4 4 3 5% 5% 32%	2600
May	1st to 10th	Day	17% 7% 2 6% 4 4 4 4 5% 6% 41%	4432
	11th to 20th	Day	14% 7% 2 6% 4 4 4 4 5% 7% 43%	4400
	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 5% 5% 37%	2048
November	1st to 10th	Day	13% 10% 3 9% 6% 5% 4 4 6% 5% 35%	1624
	11th to 20th	Day	13% 16% 6% 10% 5% 4 4 3 5% 6% 28%	1600
	21st to end	Day	14% 12% 4 8% 5% 4 5% 5% 5% 6% 32%	1600
December	1st to 10th	Day	9% 11% 5% 15% 12% 8% 5% 4 5% 5% 21%	2610
	11th to 20th	Day	11% 17% 7% 10% 5% 5% 4 3 5% 6% 28%	3008
	21st to end	Day	20% 18% 8% 19% 6% 4 3 3 3 4 14%	3982
January	1st to 10th	Night	8% 9% 5% 15% 9% 5% 4 3 4 6% 33%	6348
	11th to 20th	Night	6% 11% 5% 11% 7% 7% 10% 8% 7% 6% 22%	6360
	21st to end	Night	7% 18% 6% 9% 5% 4 4 3 5% 6% 32%	6513
February	1st to 10th	Night	7% 12% 5% 9% 6% 5% 5% 4 5% 7% 36%	2600
	11th to 20th	Night	6% 10% 4 9% 6% 5% 6% 4 6% 7% 39%	2533
	21st to end	Night	12% 11% 3 8% 7% 4 6% 3 4 6% 36%	2091
March	1st to 10th	Night	9% 7% 2 6% 4 4 4 3 4 7% 48%	5081
	11th to 20th	Night	10% 8% 3 8% 5% 4 5% 5% 8% 9% 36%	4980
	21st to end	Night	23% 11% 4 10% 4 4 3 3 5% 5% 28%	5386
April	1st to 10th	Night	16% 11% 3 7% 4 4 4 3 5% 7% 37%	2000
	11th to 20th	Night	20% 10% 3 6% 3 4 4 3 4 5% 38%	1946
	21st to end	Night	20% 10% 3 6% 4 4 3 4 5% 6% 35%	1800
May	1st to 10th	Night	12% 8% 3 8% 5% 4 4 4 5% 6% 41%	2693
	11th to 20th	Night	14% 5% 2 4 3 3 4 2 6% 7% 50%	2511
	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% 38%	2669
	11th to 20th	Night	14% 12% 4 11% 6% 5% 4 3 4 5% 33%	2800
	21st to end	Night	13% 10% 3 9% 5% 4 4 4 6% 7% 34%	2800
December	1st to 10th	Night	7% 10% 4 15% 8% 7% 5% 4 6% 7% 27%	4580
	11th to 20th	Night	10% 17% 6% 14% 6% 5% 5% 5% 5% 5% 23%	5199
	21st to end	Night	21% 18% 8% 15% 5% 4 3 3 3 4 18%	6996

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	58% 5% 9% 18% 10%	3618
	11th to 20th	Day	59% 4 11% 17% 9%	3620
	21st to end	Day	54% 6% 15% 17% 8%	4460
February	1st to 10th	Day	51% 6% 12% 22% 8% 2	1800
	11th to 20th	Day	48% 5% 12% 25% 9% 1	1763
	21st to end	Day	50% 5% 12% 21% 11% 1	1537
March	1st to 10th	Day	39% 5% 18% 25% 10% 3	4802
	11th to 20th	Day	43% 3 16% 29% 9%	4980
	21st to end	Day	57% 5% 9% 20% 8% 1	5545
April	1st to 10th	Day	50% 5% 11% 19% 14% 1	2400
	11th to 20th	Day	54% 5% 9% 18% 12% 2	2399
	21st to end	Day	54% 5% 10% 20% 10%	2600
May	1st to 10th	Day	43% 5% 12% 24% 15% 1	4471
	11th to 20th	Day	39% 6% 12% 28% 13% 2	4404
	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	31% 4 11% 34% 19%	3160
	11th to 20th	Day	40% 4 11% 28% 15% 2	3140
	21st to end	Day	46% 4 16% 26% 8%	3350
November	1st to 10th	Day	50% 5% 12% 20% 12% 1	1624
	11th to 20th	Day	57% 6% 14% 15% 8%	1600
	21st to end	Day	50% 7% 15% 21% 5% 2	1600
December	1st to 10th	Day	63% 6% 12% 13% 4 1	2610
	11th to 20th	Day	57% 5% 11% 20% 7%	3005
	21st to end	Day	76% 4 7% 8% 5%	3982
January	1st to 10th	Night	54% 4 11% 19% 11% 1	6348
	11th to 20th	Night	58% 6% 10% 15% 10%	6360
	21st to end	Night	52% 5% 13% 23% 6%	6513
February	1st to 10th	Night	47% 5% 14% 22% 11% 1	2600
	11th to 20th	Night	43% 6% 14% 24% 10% 1	2534
	21st to end	Night	48% 4 13% 21% 12% 1	2091
March	1st to 10th	Night	37% 4 14% 23% 18% 4	5081
	11th to 20th	Night	41% 5% 16% 25% 13%	4980
	21st to end	Night	59% 3 10% 16% 11% 1	5386
April	1st to 10th	Night	47% 5% 10% 22% 16% 1	2000
	11th to 20th	Night	48% 5% 8% 21% 15% 2	1946
	21st to end	Night	49% 7% 8% 21% 14% 2	1800
May	1st to 10th	Night	42% 6% 11% 22% 18% 2	2719
	11th to 20th	Night	34% 6% 11% 26% 20% 3	2512
	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	24% 3 7% 36% 25% 4	3800
	11th to 20th	Night	34% 4 12% 27% 21% 2	3779
	21st to end	Night	44% 4 12% 26% 12%	4196
November	1st to 10th	Night	45% 5% 13% 24% 12% 1	2669
	11th to 20th	Night	53% 5% 13% 18% 10% 1	2800
	21st to end	Night	48% 7% 16% 21% 6% 1	2800
December	1st to 10th	Night	55% 7% 16% 19% 3	4580
	11th to 20th	Night	62% 5% 10% 17% 5% 1	5201
	21st to end	Night	71% 4 8% 13% 5%	6996

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% 31% 30% 11% 5%	300
	11th to 20th	Day	13% 8% 39% 32% 7% 1	300
	21st to end	Day	15% 8% 38% 23% 12% 3	330
February	1st to 10th	Day	14% 12% 42% 25% 6% 1	300
	11th to 20th	Day	14% 12% 40% 25% 7% 2	300
	21st to end	Day	17% 12% 39% 28% 4	249
March	1st to 10th	Day	18% 12% 36% 25% 8% 1	300
	11th to 20th	Day	18% 9% 36% 26% 10% 2	300
	21st to end	Day	26% 12% 29% 23% 8% 3	360
April	1st to 10th	Day	22% 16% 30% 26% 6%	500
	11th to 20th	Day	24% 16% 27% 22% 10% 1	517
	21st to end	Day	27% 10% 31% 21% 10% 3	700
May	1st to 10th	Day	18% 11% 31% 27% 11% 2	703
	11th to 20th	Day	18% 10% 29% 28% 12% 3	676
	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	21% 11% 34% 24% 10% 1	300
	11th to 20th	Day	19% 17% 40% 19% 4 1	300
	21st to end	Day	21% 12% 39% 21% 6%	300
December	1st to 10th	Day	15% 10% 41% 23% 11%	300
	11th to 20th	Day	20% 13% 37% 25% 5%	300
	21st to end	Day	28% 11% 33% 23% 3 1	330
January	1st to 10th	Night	13% 10% 35% 32% 9% 1	1000
	11th to 20th	Night	15% 7% 37% 31% 8% 1	1000
	21st to end	Night	18% 8% 37% 28% 8% 1	1100
February	1st to 10th	Night	12% 9% 39% 30% 9% 1	1000
	11th to 20th	Night	10% 10% 42% 29% 8% 1	979
	21st to end	Night	16% 9% 35% 30% 9% 1	771
March	1st to 10th	Night	15% 10% 37% 29% 9%	676
	11th to 20th	Night	16% 11% 37% 30% 6% 1	600
	21st to end	Night	23% 7% 29% 28% 10% 2	660
April	1st to 10th	Night	19% 12% 34% 30% 6%	600
	11th to 20th	Night	25% 9% 32% 26% 7% 1	593
	21st to end	Night	23% 9% 30% 28% 9% 1	600
May	1st to 10th	Night	15% 11% 32% 33% 8%	600
	11th to 20th	Night	15% 8% 30% 34% 11% 1	563
	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% 31% 30% 7%	836
November	1st to 10th	Night	18% 10% 31% 32% 9%	913
	11th to 20th	Night	19% 11% 35% 27% 7% 1	1000
	21st to end	Night	18% 12% 36% 27% 8%	1000
December	1st to 10th	Night	15% 9% 35% 32% 8% 1	1000
	11th to 20th	Night	18% 11% 37% 27% 8% 1	1000
	21st to end	Night	26% 8% 32% 26% 6% 1	1100

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