Nicolet
Clear Sky Chart
History

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

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	17% 9% 3 7% 5% 4 4 4 5% 7% 34%	101819
	Night	19% 11% 4 8% 5% 4 4 3 5% 6% 31%	97923
Transparency	Day	50% 5% 15% 21% 8% 1	105280
	Night	54% 5% 13% 19% 8% 1	102551
Seeing	Day	22% 10% 28% 25% 12% 3	14653
	Night	24% 8% 29% 29% 9% 1	23565

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	20% 15% 4 9% 4 4 3 3 4 6% 27%	2517
	11th to 20th	Day	13% 14% 6% 9% 7% 4 4 4 5% 5% 29%	2520
	21st to end	Day	12% 15% 5% 11% 6% 5% 5% 4 5% 6% 26%	2772
February	1st to 10th	Day	14% 16% 5% 9% 7% 5% 4 3 4 5% 26%	1591
	11th to 20th	Day	14% 15% 5% 9% 5% 5% 5% 3 6% 5% 26%	1796
	21st to end	Day	15% 14% 5% 9% 6% 5% 4 3 5% 5% 29%	1570
March	1st to 10th	Day	19% 11% 3 8% 6% 5% 4 4 5% 6% 30%	3116
	11th to 20th	Day	15% 16% 4 9% 5% 4 4 4 4 6% 29%	3259
	21st to end	Day	15% 11% 4 7% 5% 4 4 3 5% 5% 37%	4166
April	1st to 10th	Day	22% 10% 3 7% 4 4 4 4 5% 6% 32%	2280
	11th to 20th	Day	21% 7% 2 5% 4 5% 5% 3 5% 6% 38%	2281
	21st to end	Day	23% 10% 3 6% 4 4 4 3 5% 5% 32%	2470
May	1st to 10th	Day	21% 7% 3 7% 4 5% 4 3 5% 7% 34%	4295
	11th to 20th	Day	16% 7% 2 7% 5% 5% 5% 4 6% 8% 33%	4398
	21st to end	Day	16% 6% 3 7% 5% 5% 5% 4 6% 8% 36%	4837
June	1st to 10th	Day	21% 7% 3 7% 5% 5% 5% 4 6% 7% 31%	2660
	11th to 20th	Day	16% 6% 3 6% 5% 4 5% 4 6% 9% 37%	2660
	21st to end	Day	20% 8% 3 7% 5% 5% 5% 5% 5% 7% 31%	2660
July	1st to 10th	Day	12% 7% 2 7% 5% 5% 5% 5% 7% 9% 36%	4440
	11th to 20th	Day	13% 7% 3 7% 5% 5% 5% 4 7% 9% 37%	4440
	21st to end	Day	12% 6% 2 5% 4 4 4 4 6% 8% 45%	4814
August	1st to 10th	Day	15% 5% 2 7% 5% 5% 6% 5% 8% 11% 32%	4423
	11th to 20th	Day	17% 6% 3 6% 4 4 4 4 6% 9% 36%	4090
	21st to end	Day	18% 5% 2 6% 4 4 4 3 5% 7% 40%	4180
September	1st to 10th	Day	13% 6% 2 6% 5% 4 4 4 6% 8% 41%	2280
	11th to 20th	Day	15% 6% 2 5% 3 3 4 3 5% 6% 48%	2160
	21st to end	Day	19% 6% 1 6% 4 3 5% 4 5% 6% 41%	2090
October	1st to 10th	Day	20% 7% 3 6% 4 4 4 4 5% 7% 36%	2019
	11th to 20th	Day	22% 8% 3 8% 5% 5% 5% 4 5% 7% 29%	1800
	21st to end	Day	25% 11% 2 8% 3 3 4 3 4 6% 30%	1881
November	1st to 10th	Day	19% 10% 3 7% 6% 4 3 4 5% 6% 34%	1761
	11th to 20th	Day	20% 12% 4 9% 5% 4 4 3 4 6% 29%	1755
	21st to end	Day	23% 14% 3 6% 5% 5% 4 3 5% 6% 25%	1600
December	1st to 10th	Day	27% 14% 4 9% 5% 5% 4 3 4 3 23%	1560
	11th to 20th	Day	22% 15% 6% 9% 4 4 4 3 4 4 26%	1906
	21st to end	Day	25% 17% 5% 10% 4 3 3 3 4 5% 22%	2772
January	1st to 10th	Night	17% 17% 6% 10% 5% 4 4 3 5% 5% 25%	4429
	11th to 20th	Night	13% 14% 5% 12% 7% 6% 5% 4 5% 5% 24%	4440
	21st to end	Night	14% 15% 5% 12% 7% 5% 5% 3 5% 5% 24%	4884
February	1st to 10th	Night	14% 15% 4 11% 7% 6% 4 4 5% 5% 25%	2588
	11th to 20th	Night	14% 15% 5% 12% 7% 5% 4 4 4 5% 27%	2270
	21st to end	Night	15% 15% 3 8% 6% 5% 4 3 4 4 33%	1884
March	1st to 10th	Night	25% 11% 3 8% 4 4 3 3 4 4 30%	3724
	11th to 20th	Night	19% 17% 6% 10% 5% 4 4 3 3 4 26%	3697
	21st to end	Night	15% 11% 4 9% 4 4 5% 3 4 4 35%	3466
April	1st to 10th	Night	24% 11% 3 8% 4 3 4 3 5% 6% 29%	1900
	11th to 20th	Night	22% 8% 2 6% 5% 3 5% 4 5% 5% 35%	1847
	21st to end	Night	23% 10% 4 6% 4 3 3 3 4 6% 35%	1710
May	1st to 10th	Night	23% 8% 3 8% 5% 4 4 3 5% 5% 30%	2674
	11th to 20th	Night	21% 7% 2 8% 4 5% 4 3 5% 6% 34%	2495
	21st to end	Night	18% 6% 2 7% 5% 4 5% 4 6% 9% 34%	2738
June	1st to 10th	Night	20% 7% 3 5% 4 4 4 4 7% 7% 33%	1520
	11th to 20th	Night	19% 6% 2 6% 4 4 4 4 5% 8% 37%	1520
	21st to end	Night	20% 7% 3 6% 5% 5% 5% 5% 6% 8% 31%	1520
July	1st to 10th	Night	13% 5% 3 7% 7% 6% 6% 5% 6% 10% 31%	2520
	11th to 20th	Night	17% 6% 2 6% 4 4 4 5% 6% 8% 38%	2520
	21st to end	Night	13% 5% 2 6% 4 4 4 3 6% 7% 45%	2739
August	1st to 10th	Night	15% 7% 3 8% 6% 5% 5% 4 7% 7% 33%	2506
	11th to 20th	Night	17% 7% 2 8% 5% 4 4 4 5% 7% 37%	2705
	21st to end	Night	19% 6% 3 7% 4 4 4 4 5% 6% 39%	3473
September	1st to 10th	Night	15% 5% 2 6% 4 3 4 3 5% 8% 45%	1900
	11th to 20th	Night	17% 5% 1 5% 4 4 3 2 5% 6% 49%	2019
	21st to end	Night	18% 6% 3 6% 4 4 4 4 4 6% 42%	2090
October	1st to 10th	Night	19% 7% 2 6% 5% 4 4 4 5% 5% 39%	2157
	11th to 20th	Night	22% 9% 3 7% 4 4 4 4 4 6% 34%	2380
	21st to end	Night	25% 9% 3 7% 4 4 4 4 4 6% 30%	2717
November	1st to 10th	Night	21% 10% 3 8% 5% 5% 5% 3 5% 5% 31%	2537
	11th to 20th	Night	20% 11% 4 9% 5% 5% 3 3 5% 5% 30%	2645
	21st to end	Night	25% 15% 3 8% 5% 4 4 2 4 4 26%	2800
December	1st to 10th	Night	22% 15% 5% 10% 6% 4 4 3 4 4 21%	2737
	11th to 20th	Night	23% 15% 5% 9% 5% 3 3 3 4 5% 25%	3288
	21st to end	Night	27% 18% 5% 9% 3 2 3 2 3 4 24%	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	62% 6% 14% 16% 3	2518
	11th to 20th	Day	58% 6% 10% 20% 6%	2520
	21st to end	Day	59% 5% 13% 16% 5% 1	2772
February	1st to 10th	Day	61% 4 10% 18% 5% 1	1591
	11th to 20th	Day	59% 5% 14% 14% 7% 1	1805
	21st to end	Day	58% 5% 10% 17% 8% 2	1570
March	1st to 10th	Day	56% 6% 10% 18% 7% 1	3119
	11th to 20th	Day	57% 5% 14% 12% 10% 2	3259
	21st to end	Day	49% 4 9% 22% 13% 3	4166
April	1st to 10th	Day	55% 5% 11% 17% 10% 2	2280
	11th to 20th	Day	48% 5% 10% 23% 12% 2	2281
	21st to end	Day	54% 4 9% 17% 11% 3	2470
May	1st to 10th	Day	51% 4 12% 21% 11% 1	4309
	11th to 20th	Day	47% 8% 19% 16% 9% 1	4402
	21st to end	Day	45% 7% 12% 22% 13% 1	4837
June	1st to 10th	Day	50% 7% 12% 20% 9% 2	2660
	11th to 20th	Day	43% 7% 14% 22% 12% 2	2660
	21st to end	Day	53% 7% 13% 19% 9%	2660
July	1st to 10th	Day	44% 5% 17% 25% 8%	4370
	11th to 20th	Day	45% 4 20% 25% 6%	4365
	21st to end	Day	38% 5% 17% 31% 9%	4661
August	1st to 10th	Day	47% 6% 20% 22% 6%	4409
	11th to 20th	Day	46% 5% 23% 22% 5%	4130
	21st to end	Day	44% 5% 16% 21% 14% 1	4180
September	1st to 10th	Day	39% 6% 18% 26% 10% 1	2280
	11th to 20th	Day	37% 5% 16% 31% 11% 1	2160
	21st to end	Day	43% 6% 14% 27% 10%	2090
October	1st to 10th	Day	46% 3 16% 29% 5%	3357
	11th to 20th	Day	49% 5% 19% 24% 4	2964
	21st to end	Day	47% 3 21% 22% 7%	3081
November	1st to 10th	Day	52% 5% 14% 21% 8%	1761
	11th to 20th	Day	57% 4 13% 17% 9%	1755
	21st to end	Day	62% 5% 15% 15% 4	1600
December	1st to 10th	Day	67% 3 13% 12% 5%	1560
	11th to 20th	Day	62% 5% 8% 20% 5%	1906
	21st to end	Day	67% 5% 11% 9% 7%	2772
January	1st to 10th	Night	63% 5% 16% 12% 4	4429
	11th to 20th	Night	63% 5% 13% 15% 4 1	4440
	21st to end	Night	64% 5% 12% 14% 5%	4884
February	1st to 10th	Night	62% 4 9% 16% 7% 1	2588
	11th to 20th	Night	60% 4 10% 16% 9% 1	2272
	21st to end	Night	56% 4 11% 16% 12% 2	1884
March	1st to 10th	Night	56% 5% 10% 17% 8% 3	3734
	11th to 20th	Night	63% 4 8% 13% 9% 2	3698
	21st to end	Night	53% 4 9% 22% 10% 3	3466
April	1st to 10th	Night	56% 4 9% 17% 12% 2	1900
	11th to 20th	Night	50% 5% 9% 20% 14% 2	1847
	21st to end	Night	52% 4 9% 19% 14% 3	1710
May	1st to 10th	Night	55% 5% 11% 18% 9% 2	2680
	11th to 20th	Night	49% 7% 14% 18% 10% 2	2496
	21st to end	Night	45% 6% 11% 18% 17% 2	2739
June	1st to 10th	Night	48% 5% 12% 21% 12% 1	1520
	11th to 20th	Night	44% 7% 12% 21% 13% 3	1520
	21st to end	Night	50% 8% 11% 19% 12% 1	1520
July	1st to 10th	Night	47% 6% 17% 20% 10%	2480
	11th to 20th	Night	44% 6% 20% 23% 8%	2472
	21st to end	Night	39% 5% 21% 24% 11%	2651
August	1st to 10th	Night	50% 6% 14% 25% 5%	2496
	11th to 20th	Night	47% 6% 18% 24% 6%	2731
	21st to end	Night	47% 4 12% 23% 14%	3473
September	1st to 10th	Night	39% 5% 16% 26% 13% 1	1900
	11th to 20th	Night	37% 4 14% 32% 11% 1	2019
	21st to end	Night	44% 5% 10% 27% 13% 1	2090
October	1st to 10th	Night	50% 4 13% 25% 9%	3599
	11th to 20th	Night	48% 4 14% 28% 6%	3955
	21st to end	Night	49% 4 16% 20% 10% 2	4467
November	1st to 10th	Night	54% 5% 13% 19% 7% 1	2537
	11th to 20th	Night	57% 4 12% 17% 9% 1	2645
	21st to end	Night	62% 4 12% 16% 5%	2800
December	1st to 10th	Night	68% 4 12% 12% 4	2737
	11th to 20th	Night	63% 4 10% 18% 5%	3288
	21st to end	Night	67% 3 9% 16% 4	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	28% 14% 30% 22% 5% 1	180
	11th to 20th	Day	26% 12% 34% 22% 6% 1	180
	21st to end	Day	22% 10% 33% 27% 6% 2	198
February	1st to 10th	Day	30% 14% 37% 15% 4 1	213
	11th to 20th	Day	21% 12% 34% 27% 4	404
	21st to end	Day	23% 14% 33% 25% 4	382
March	1st to 10th	Day	23% 10% 30% 28% 8%	460
	11th to 20th	Day	21% 16% 32% 22% 7% 1	460
	21st to end	Day	26% 10% 29% 23% 10% 2	506
April	1st to 10th	Day	27% 12% 24% 27% 9% 1	460
	11th to 20th	Day	27% 15% 25% 20% 10% 2	452
	21st to end	Day	28% 11% 33% 17% 8% 2	460
May	1st to 10th	Day	24% 12% 32% 19% 11% 2	463
	11th to 20th	Day	18% 8% 29% 25% 15% 4	487
	21st to end	Day	20% 12% 33% 20% 12% 3	529
June	1st to 10th	Day	22% 9% 26% 27% 12% 4	490
	11th to 20th	Day	17% 10% 28% 26% 16% 3	490
	21st to end	Day	22% 10% 26% 24% 15% 3	490
July	1st to 10th	Day	15% 6% 26% 29% 19% 5%	485
	11th to 20th	Day	15% 6% 28% 32% 15% 3	484
	21st to end	Day	14% 8% 24% 32% 20% 3	532
August	1st to 10th	Day	17% 7% 19% 32% 20% 5%	486
	11th to 20th	Day	16% 4 21% 32% 19% 8%	479
	21st to end	Day	17% 8% 25% 23% 17% 11%	539
September	1st to 10th	Day	15% 8% 26% 29% 14% 8%	490
	11th to 20th	Day	16% 7% 19% 28% 20% 9%	490
	21st to end	Day	19% 8% 24% 23% 19% 6%	490
October	1st to 10th	Day	20% 10% 27% 25% 15% 4	490
	11th to 20th	Day	26% 13% 27% 21% 11% 3	437
	21st to end	Day	30% 12% 27% 22% 10%	429
November	1st to 10th	Day	30% 12% 27% 23% 8% 1	395
	11th to 20th	Day	26% 12% 28% 24% 9%	355
	21st to end	Day	34% 13% 31% 15% 9%	200
December	1st to 10th	Day	33% 12% 22% 21% 9% 4	190
	11th to 20th	Day	26% 18% 33% 18% 4 1	180
	21st to end	Day	32% 18% 26% 15% 9% 1	198
January	1st to 10th	Night	28% 11% 30% 25% 6%	760
	11th to 20th	Night	27% 10% 29% 28% 6%	760
	21st to end	Night	18% 6% 33% 35% 7%	836
February	1st to 10th	Night	22% 8% 35% 28% 6% 1	760
	11th to 20th	Night	21% 11% 38% 24% 5% 1	743
	21st to end	Night	23% 10% 32% 30% 5%	628
March	1st to 10th	Night	24% 9% 30% 31% 5%	760
	11th to 20th	Night	26% 9% 34% 24% 6% 1	760
	21st to end	Night	22% 9% 32% 29% 7% 1	836
April	1st to 10th	Night	30% 8% 26% 30% 6%	760
	11th to 20th	Night	26% 11% 30% 26% 7%	723
	21st to end	Night	26% 12% 29% 26% 6%	570
May	1st to 10th	Night	26% 7% 30% 30% 7%	475
	11th to 20th	Night	23% 7% 29% 33% 8% 1	374
	21st to end	Night	21% 6% 36% 28% 9%	411
June	1st to 10th	Night	24% 4 29% 34% 7% 1	380
	11th to 20th	Night	21% 4 27% 36% 12%	380
	21st to end	Night	22% 4 27% 36% 11% 1	380
July	1st to 10th	Night	13% 5% 26% 42% 14% 1	370
	11th to 20th	Night	13% 3 22% 47% 14% 1	368
	21st to end	Night	15% 4 21% 45% 14%	416
August	1st to 10th	Night	16% 4 17% 42% 20% 1	378
	11th to 20th	Night	15% 4 21% 38% 20% 2	509
	21st to end	Night	17% 5% 24% 32% 20% 2	833
September	1st to 10th	Night	17% 5% 25% 38% 13% 1	760
	11th to 20th	Night	20% 5% 18% 33% 22% 1	760
	21st to end	Night	20% 6% 26% 31% 15% 3	760
October	1st to 10th	Night	22% 6% 30% 29% 13% 1	760
	11th to 20th	Night	26% 8% 28% 29% 9% 1	760
	21st to end	Night	28% 9% 32% 26% 5%	836
November	1st to 10th	Night	26% 12% 29% 25% 7%	780
	11th to 20th	Night	24% 10% 33% 21% 11% 1	800
	21st to end	Night	31% 11% 28% 23% 6% 1	800
December	1st to 10th	Night	32% 9% 29% 23% 6% 1	783
	11th to 20th	Night	26% 11% 31% 24% 7% 1	760
	21st to end	Night	33% 13% 28% 20% 7%	836

Page generated at 2024-12-03 06:45:10. Version ac07

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