Monroe CAM
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Monroe CAM clear sky chart from 2005-11-06 to 2024-12-02.

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% 7% 2 6% 4 4 4 4 6% 7% 39%	101531
	Night	17% 7% 2 6% 4 4 4 3 5% 6% 42%	98084
Transparency	Day	42% 5% 11% 23% 16% 2	105076
	Night	41% 5% 11% 24% 17% 3	102628
Seeing	Day	23% 15% 30% 21% 9% 3	15102
	Night	20% 14% 31% 26% 9% 1	24323

By Month

Percentage Cloud Cover NE (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	14% 9% 2 5% 4 4 3 3 4 5% 46%	2517
	11th to 20th	Day	15% 10% 3 8% 5% 4 4 3 5% 7% 37%	2520
	21st to end	Day	22% 11% 3 6% 5% 3 4 3 4 4 34%	3092
February	1st to 10th	Day	16% 8% 3 7% 5% 4 3 3 5% 6% 40%	1710
	11th to 20th	Day	16% 8% 3 6% 4 4 4 3 4 6% 41%	1846
	21st to end	Day	19% 9% 3 7% 4 4 3 4 5% 5% 37%	1570
March	1st to 10th	Day	27% 8% 3 5% 3 4 3 2 4 5% 36%	3116
	11th to 20th	Day	9% 5% 2 6% 5% 5% 5% 4 6% 7% 46%	3384
	21st to end	Day	21% 5% 2 6% 3 4 3 2 4 6% 43%	4100
April	1st to 10th	Day	17% 8% 3 6% 4 4 4 3 6% 6% 39%	2280
	11th to 20th	Day	16% 6% 2 5% 4 4 4 3 6% 9% 40%	2254
	21st to end	Day	17% 6% 2 6% 4 4 4 4 6% 7% 40%	2280
May	1st to 10th	Day	26% 8% 3 6% 4 4 4 4 5% 8% 29%	4074
	11th to 20th	Day	25% 8% 2 7% 5% 5% 4 3 4 6% 30%	4384
	21st to end	Day	13% 5% 2 5% 4 4 5% 4 6% 8% 43%	4837
June	1st to 10th	Day	14% 6% 2 5% 4 5% 5% 5% 7% 9% 38%	2660
	11th to 20th	Day	13% 7% 2 7% 4 5% 6% 4 6% 8% 38%	2660
	21st to end	Day	11% 6% 3 6% 5% 5% 6% 4 6% 9% 40%	2660
July	1st to 10th	Day	8% 6% 2 8% 5% 6% 6% 6% 8% 11% 35%	4440
	11th to 20th	Day	11% 7% 2 6% 5% 5% 6% 4 8% 10% 37%	4440
	21st to end	Day	13% 8% 3 8% 6% 6% 6% 5% 6% 9% 32%	4814
August	1st to 10th	Day	19% 7% 2 7% 4 5% 5% 5% 7% 9% 30%	4087
	11th to 20th	Day	13% 6% 2 7% 4 5% 4 4 6% 8% 40%	3730
	21st to end	Day	10% 6% 2 5% 4 4 4 3 6% 9% 47%	4180
September	1st to 10th	Day	13% 6% 2 7% 4 3 5% 2 5% 7% 44%	2280
	11th to 20th	Day	12% 5% 2 5% 4 4 3 3 5% 7% 49%	2214
	21st to end	Day	19% 7% 2 7% 3 4 5% 3 5% 6% 39%	2090
October	1st to 10th	Day	18% 7% 2 5% 3 4 4 3 5% 6% 43%	1958
	11th to 20th	Day	15% 6% 2 5% 3 3 3 3 4 6% 49%	1900
	21st to end	Day	19% 6% 2 5% 3 3 3 2 4 6% 46%	1972
November	1st to 10th	Day	12% 7% 2 5% 3 2 3 2 4 6% 52%	1761
	11th to 20th	Day	16% 6% 2 5% 2 3 4 3 6% 5% 48%	1800
	21st to end	Day	15% 6% 2 5% 4 3 3 3 5% 7% 45%	1715
December	1st to 10th	Day	18% 8% 3 6% 4 4 3 3 6% 7% 38%	1528
	11th to 20th	Day	19% 8% 3 5% 3 3 4 3 5% 5% 43%	1906
	21st to end	Day	17% 7% 2 6% 5% 5% 5% 4 6% 7% 34%	2772
January	1st to 10th	Night	16% 8% 2 5% 3 3 4 3 5% 6% 46%	4429
	11th to 20th	Night	17% 9% 2 6% 3 4 3 2 4 6% 43%	4440
	21st to end	Night	24% 10% 3 6% 4 4 3 3 4 5% 35%	4560
February	1st to 10th	Night	16% 9% 3 6% 3 4 4 3 5% 6% 41%	2470
	11th to 20th	Night	17% 9% 3 6% 3 3 3 4 4 5% 41%	2218
	21st to end	Night	19% 7% 2 5% 4 3 3 3 5% 6% 42%	1884
March	1st to 10th	Night	23% 10% 2 6% 4 3 3 3 3 5% 37%	3724
	11th to 20th	Night	12% 6% 2 6% 4 4 4 3 5% 6% 48%	3558
	21st to end	Night	20% 9% 3 6% 4 3 2 3 4 4 43%	3531
April	1st to 10th	Night	17% 7% 3 6% 4 4 4 4 6% 6% 40%	1900
	11th to 20th	Night	16% 7% 3 7% 4 4 4 3 5% 6% 41%	1875
	21st to end	Night	18% 7% 2 5% 3 3 3 4 5% 7% 43%	1900
May	1st to 10th	Night	22% 10% 4 8% 3 3 4 3 5% 8% 29%	2850
	11th to 20th	Night	24% 9% 3 7% 4 4 3 3 5% 6% 31%	2537
	21st to end	Night	14% 7% 3 5% 4 4 4 4 6% 10% 41%	2738
June	1st to 10th	Night	14% 7% 2 6% 4 3 4 5% 6% 8% 41%	1520
	11th to 20th	Night	11% 6% 2 6% 6% 4 4 5% 6% 8% 41%	1520
	21st to end	Night	9% 5% 2 7% 5% 5% 5% 5% 7% 10% 40%	1520
July	1st to 10th	Night	8% 5% 3 8% 6% 6% 6% 4 8% 9% 38%	2520
	11th to 20th	Night	12% 6% 3 6% 4 5% 5% 5% 7% 10% 37%	2520
	21st to end	Night	15% 7% 3 6% 5% 4 5% 4 7% 8% 35%	2739
August	1st to 10th	Night	23% 7% 2 6% 4 4 4 4 7% 7% 32%	2807
	11th to 20th	Night	13% 6% 3 7% 5% 3 5% 4 6% 7% 42%	3097
	21st to end	Night	10% 5% 2 5% 4 4 4 3 5% 8% 51%	3476
September	1st to 10th	Night	14% 6% 3 7% 4 4 3 4 5% 6% 45%	1900
	11th to 20th	Night	12% 5% 2 5% 3 3 3 3 4 7% 52%	1964
	21st to end	Night	19% 7% 2 6% 3 4 3 3 5% 6% 41%	2090
October	1st to 10th	Night	18% 6% 2 5% 4 3 4 3 5% 6% 43%	2218
	11th to 20th	Night	14% 4 2 4 4 4 4 3 4 7% 51%	2280
	21st to end	Night	19% 6% 3 5% 3 3 3 3 5% 5% 46%	2624
November	1st to 10th	Night	11% 5% 2 5% 4 3 3 3 4 6% 54%	2537
	11th to 20th	Night	17% 6% 2 6% 3 3 3 3 4 5% 48%	2600
	21st to end	Night	13% 7% 2 5% 4 4 4 3 6% 6% 45%	2680
December	1st to 10th	Night	20% 7% 2 6% 4 3 3 3 6% 6% 39%	2686
	11th to 20th	Night	18% 6% 2 6% 4 4 3 3 5% 6% 42%	3288
	21st to end	Night	18% 8% 3 7% 4 4 4 3 4 5% 38%	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	42% 3 10% 27% 14% 4	2518
	11th to 20th	Day	48% 4 9% 22% 14% 2	2520
	21st to end	Day	54% 4 9% 21% 10% 2	3092
February	1st to 10th	Day	46% 4 11% 24% 13% 2	1710
	11th to 20th	Day	46% 4 7% 24% 16% 3	1855
	21st to end	Day	49% 4 8% 21% 14% 4	1570
March	1st to 10th	Day	51% 4 8% 26% 9% 2	3119
	11th to 20th	Day	34% 6% 10% 31% 16% 3	3384
	21st to end	Day	44% 4 7% 17% 22% 5%	4100
April	1st to 10th	Day	45% 5% 9% 19% 16% 5%	2280
	11th to 20th	Day	40% 6% 11% 22% 18% 3	2254
	21st to end	Day	43% 5% 10% 20% 19% 4	2280
May	1st to 10th	Day	54% 5% 11% 16% 11% 2	4088
	11th to 20th	Day	55% 5% 12% 19% 9% 1	4388
	21st to end	Day	37% 7% 10% 26% 18% 2	4837
June	1st to 10th	Day	41% 7% 12% 23% 16% 2	2660
	11th to 20th	Day	42% 7% 12% 24% 12% 3	2660
	21st to end	Day	40% 6% 12% 23% 17% 1	2660
July	1st to 10th	Day	41% 10% 14% 21% 14% 1	4370
	11th to 20th	Day	40% 8% 15% 21% 14% 1	4365
	21st to end	Day	48% 7% 10% 18% 15% 1	4661
August	1st to 10th	Day	49% 8% 12% 22% 10% 1	4073
	11th to 20th	Day	40% 7% 13% 26% 13% 1	3766
	21st to end	Day	33% 6% 11% 27% 21% 2	4180
September	1st to 10th	Day	39% 5% 11% 21% 21% 3	2280
	11th to 20th	Day	35% 5% 9% 24% 25% 3	2214
	21st to end	Day	46% 4 9% 18% 20% 3	2090
October	1st to 10th	Day	37% 5% 10% 18% 25% 5%	3257
	11th to 20th	Day	25% 2 10% 25% 32% 6%	3140
	21st to end	Day	27% 3 13% 25% 27% 4	3223
November	1st to 10th	Day	35% 3 11% 26% 22% 3	1761
	11th to 20th	Day	38% 4 8% 25% 22% 3	1800
	21st to end	Day	39% 3 12% 30% 13% 3	1715
December	1st to 10th	Day	45% 4 14% 22% 14% 1	1528
	11th to 20th	Day	44% 4 11% 25% 13% 2	1906
	21st to end	Day	46% 7% 10% 24% 12% 1	2772
January	1st to 10th	Night	40% 4 9% 31% 13% 4	4429
	11th to 20th	Night	44% 3 11% 25% 14% 3	4440
	21st to end	Night	52% 4 7% 23% 12% 2	4560
February	1st to 10th	Night	44% 4 14% 24% 13% 2	2470
	11th to 20th	Night	45% 3 8% 20% 19% 5%	2220
	21st to end	Night	43% 3 7% 24% 18% 4	1884
March	1st to 10th	Night	50% 3 8% 24% 12% 3	3734
	11th to 20th	Night	37% 5% 12% 25% 18% 3	3559
	21st to end	Night	46% 4 6% 17% 22% 6%	3531
April	1st to 10th	Night	44% 4 9% 20% 18% 5%	1900
	11th to 20th	Night	44% 4 8% 20% 21% 3	1875
	21st to end	Night	40% 4 10% 20% 21% 5%	1900
May	1st to 10th	Night	53% 6% 10% 19% 11% 1	2856
	11th to 20th	Night	53% 6% 13% 16% 10% 2	2538
	21st to end	Night	39% 7% 14% 22% 15% 2	2739
June	1st to 10th	Night	39% 6% 11% 22% 20% 2	1520
	11th to 20th	Night	40% 7% 13% 27% 12% 1	1520
	21st to end	Night	37% 7% 15% 23% 15% 2	1520
July	1st to 10th	Night	40% 9% 18% 20% 12% 2	2480
	11th to 20th	Night	39% 8% 16% 25% 11% 1	2472
	21st to end	Night	44% 7% 15% 17% 15% 2	2651
August	1st to 10th	Night	48% 8% 18% 17% 8% 1	2797
	11th to 20th	Night	40% 6% 12% 30% 12% 1	3127
	21st to end	Night	31% 5% 11% 30% 21% 2	3476
September	1st to 10th	Night	40% 5% 11% 23% 19% 2	1900
	11th to 20th	Night	33% 5% 10% 23% 26% 4	1964
	21st to end	Night	43% 5% 7% 23% 21% 2	2090
October	1st to 10th	Night	37% 5% 11% 23% 22% 2	3699
	11th to 20th	Night	24% 3 9% 28% 30% 5%	3779
	21st to end	Night	27% 4 10% 31% 25% 3	4323
November	1st to 10th	Night	33% 3 11% 25% 23% 4	2537
	11th to 20th	Night	41% 3 7% 24% 20% 5%	2600
	21st to end	Night	39% 3 13% 27% 17% 2	2680
December	1st to 10th	Night	45% 4 11% 24% 15% 2	2686
	11th to 20th	Night	42% 4 12% 20% 18% 4	3288
	21st to end	Night	47% 5% 10% 25% 13% 1	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	31% 21% 31% 14% 2 2	180
	11th to 20th	Day	39% 27% 23% 11% 1	180
	21st to end	Day	28% 24% 32% 11% 4	288
February	1st to 10th	Day	29% 28% 31% 10% 2	270
	11th to 20th	Day	32% 23% 34% 9% 1	454
	21st to end	Day	30% 24% 30% 13% 2	382
March	1st to 10th	Day	30% 22% 29% 16% 3	460
	11th to 20th	Day	28% 24% 31% 13% 3 1	460
	21st to end	Day	30% 23% 30% 11% 4 1	506
April	1st to 10th	Day	28% 26% 29% 11% 5% 1	460
	11th to 20th	Day	26% 17% 36% 14% 5% 2	452
	21st to end	Day	31% 20% 29% 13% 4 2	460
May	1st to 10th	Day	33% 15% 31% 13% 6% 1	463
	11th to 20th	Day	24% 15% 34% 19% 7% 1	487
	21st to end	Day	21% 10% 25% 30% 12% 2	529
June	1st to 10th	Day	17% 12% 32% 27% 10% 2	490
	11th to 20th	Day	18% 11% 34% 26% 10% 2	490
	21st to end	Day	16% 10% 34% 28% 11% 1	490
July	1st to 10th	Day	13% 6% 29% 30% 17% 6%	485
	11th to 20th	Day	10% 4 26% 37% 20% 4	484
	21st to end	Day	15% 7% 30% 32% 13% 3	532
August	1st to 10th	Day	13% 6% 26% 34% 15% 6%	486
	11th to 20th	Day	14% 5% 25% 35% 18% 4	479
	21st to end	Day	14% 5% 30% 30% 13% 8%	539
September	1st to 10th	Day	17% 10% 29% 23% 15% 7%	490
	11th to 20th	Day	14% 8% 29% 29% 12% 8%	490
	21st to end	Day	25% 10% 30% 22% 8% 5%	490
October	1st to 10th	Day	26% 8% 26% 22% 12% 6%	490
	11th to 20th	Day	18% 17% 30% 24% 8% 3	490
	21st to end	Day	22% 16% 32% 17% 11% 2	476
November	1st to 10th	Day	19% 15% 35% 18% 10% 3	395
	11th to 20th	Day	25% 18% 33% 19% 5% 1	400
	21st to end	Day	24% 18% 35% 15% 7% 1	315
December	1st to 10th	Day	27% 27% 29% 10% 7%	182
	11th to 20th	Day	39% 19% 28% 9% 4	180
	21st to end	Day	33% 14% 32% 16% 5% 1	198
January	1st to 10th	Night	21% 24% 35% 17% 4	760
	11th to 20th	Night	25% 20% 31% 21% 3	760
	21st to end	Night	21% 23% 34% 20% 2	836
February	1st to 10th	Night	22% 20% 35% 22% 2	760
	11th to 20th	Night	25% 26% 35% 13% 1	743
	21st to end	Night	26% 22% 34% 17% 2	628
March	1st to 10th	Night	24% 21% 33% 18% 4	760
	11th to 20th	Night	24% 21% 33% 17% 4	760
	21st to end	Night	22% 16% 40% 17% 5%	836
April	1st to 10th	Night	22% 23% 33% 18% 4	760
	11th to 20th	Night	21% 17% 39% 20% 4	751
	21st to end	Night	22% 15% 37% 22% 4	760
May	1st to 10th	Night	25% 16% 32% 22% 5% 1	586
	11th to 20th	Night	23% 10% 37% 25% 5%	403
	21st to end	Night	17% 6% 27% 37% 10% 2	411
June	1st to 10th	Night	17% 7% 29% 37% 9% 1	380
	11th to 20th	Night	13% 7% 29% 40% 11%	380
	21st to end	Night	11% 4 31% 44% 11%	380
July	1st to 10th	Night	12% 4 26% 41% 15% 1	370
	11th to 20th	Night	10% 4 24% 43% 18% 1	368
	21st to end	Night	12% 2 30% 42% 13%	416
August	1st to 10th	Night	14% 2 21% 42% 18% 2	549
	11th to 20th	Night	13% 4 20% 40% 20% 3	750
	21st to end	Night	15% 3 20% 39% 21% 2	836
September	1st to 10th	Night	16% 3 28% 34% 17% 2	760
	11th to 20th	Night	16% 4 22% 33% 21% 4	760
	21st to end	Night	22% 6% 24% 31% 16% 1	760
October	1st to 10th	Night	22% 8% 26% 27% 14% 4	760
	11th to 20th	Night	17% 14% 29% 30% 11%	760
	21st to end	Night	23% 11% 34% 24% 8%	836
November	1st to 10th	Night	16% 12% 36% 26% 10% 1	780
	11th to 20th	Night	20% 17% 32% 23% 8%	800
	21st to end	Night	19% 19% 34% 21% 7%	800
December	1st to 10th	Night	27% 18% 31% 17% 7% 1	768
	11th to 20th	Night	22% 19% 35% 20% 4	760
	21st to end	Night	23% 18% 33% 23% 3	836

Page generated at 2024-11-29 10:43:04. Version ac07

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