Fond du Lac
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Fond du Lac clear sky chart from 2005-11-06 to 2024-11-05.

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% 4 4 4 5% 7% 37%	101434
	Night	13% 10% 4 8% 5% 4 4 4 5% 6% 38%	97699
Transparency	Day	44% 5% 12% 25% 13% 1	104966
	Night	46% 5% 11% 23% 13% 2	102308
Seeing	Day	16% 11% 30% 26% 14% 4	15940
	Night	17% 10% 32% 30% 11% 1	25791

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	11% 14% 7% 13% 6% 5% 4 4 5% 4 26%	2527
	11th to 20th	Day	10% 14% 5% 15% 6% 5% 8% 8% 5% 6% 19%	2530
	21st to end	Day	17% 17% 7% 15% 5% 3 4 3 3 5% 21%	2784
February	1st to 10th	Day	10% 14% 5% 10% 6% 5% 5% 3 5% 7% 29%	1710
	11th to 20th	Day	12% 12% 3 8% 5% 5% 5% 4 4 7% 36%	1814
	21st to end	Day	12% 15% 4 8% 6% 5% 4 4 4 6% 31%	1570
March	1st to 10th	Day	13% 8% 2 6% 3 4 4 4 5% 7% 44%	3120
	11th to 20th	Day	11% 7% 3 9% 5% 4 4 3 5% 6% 43%	3275
	21st to end	Day	20% 13% 4 11% 5% 4 3 3 3 5% 30%	4165
April	1st to 10th	Day	16% 14% 3 7% 5% 4 4 3 5% 7% 31%	2280
	11th to 20th	Day	19% 11% 3 6% 5% 4 4 4 5% 6% 34%	2254
	21st to end	Day	19% 9% 3 7% 5% 4 4 4 5% 5% 33%	2408
May	1st to 10th	Day	13% 8% 2 6% 4 5% 5% 4 6% 7% 40%	4168
	11th to 20th	Day	12% 5% 2 6% 4 4 4 3 5% 8% 46%	4399
	21st to end	Day	13% 6% 3 7% 5% 4 4 4 6% 8% 40%	4824
June	1st to 10th	Day	11% 6% 2 5% 5% 4 5% 4 7% 8% 44%	2660
	11th to 20th	Day	11% 6% 2 7% 5% 4 4 4 6% 9% 42%	2660
	21st to end	Day	11% 6% 2 5% 4 4 4 4 7% 9% 44%	2660
July	1st to 10th	Day	12% 6% 3 6% 5% 5% 5% 5% 7% 10% 36%	4440
	11th to 20th	Day	5% 3 1 5% 4 5% 5% 5% 8% 11% 48%	4440
	21st to end	Day	8% 6% 2 5% 5% 5% 5% 4 6% 9% 46%	4813
August	1st to 10th	Day	9% 6% 2 7% 4 5% 6% 4 6% 9% 41%	4423
	11th to 20th	Day	13% 5% 2 5% 3 4 5% 4 6% 8% 44%	3858
	21st to end	Day	11% 7% 3 6% 4 5% 4 4 5% 8% 43%	4180
September	1st to 10th	Day	12% 6% 3 7% 4 4 4 4 5% 8% 45%	2280
	11th to 20th	Day	12% 5% 2 6% 4 4 4 3 5% 8% 48%	2180
	21st to end	Day	14% 7% 2 7% 4 5% 4 3 5% 8% 41%	2090
October	1st to 10th	Day	15% 6% 2 6% 4 4 4 3 5% 7% 44%	1995
	11th to 20th	Day	19% 11% 3 7% 5% 4 5% 3 5% 7% 30%	1872
	21st to end	Day	17% 12% 3 8% 4 5% 3 3 5% 6% 35%	1881
November	1st to 10th	Day	13% 9% 3 6% 3 4 3 3 5% 7% 42%	1708
	11th to 20th	Day	11% 13% 4 11% 7% 6% 5% 4 5% 6% 28%	1710
	21st to end	Day	15% 13% 4 7% 6% 4 4 3 5% 5% 34%	1535
December	1st to 10th	Day	12% 12% 6% 11% 7% 6% 5% 4 6% 6% 24%	1520
	11th to 20th	Day	12% 15% 6% 11% 6% 6% 6% 4 4 7% 24%	1918
	21st to end	Day	18% 20% 8% 13% 7% 5% 4 4 4 5% 14%	2783
January	1st to 10th	Night	13% 14% 8% 12% 6% 4 3 2 3 4 32%	4428
	11th to 20th	Night	12% 14% 6% 15% 7% 5% 6% 6% 5% 4 19%	4440
	21st to end	Night	14% 19% 7% 12% 5% 4 3 3 4 5% 23%	4880
February	1st to 10th	Night	10% 15% 5% 9% 5% 6% 4 3 4 5% 34%	2470
	11th to 20th	Night	9% 10% 4 9% 5% 5% 5% 3 5% 5% 39%	2251
	21st to end	Night	15% 13% 3 7% 5% 4 4 3 5% 5% 35%	1884
March	1st to 10th	Night	15% 10% 2 6% 4 3 4 3 4 6% 42%	3733
	11th to 20th	Night	9% 8% 2 7% 5% 5% 5% 4 6% 8% 41%	3714
	21st to end	Night	20% 11% 5% 10% 4 4 4 3 4 5% 31%	3466
April	1st to 10th	Night	18% 12% 3 7% 4 4 4 3 5% 6% 35%	1900
	11th to 20th	Night	20% 9% 3 6% 4 4 4 4 4 5% 37%	1875
	21st to end	Night	16% 9% 3 7% 5% 4 4 3 6% 5% 37%	1771
May	1st to 10th	Night	14% 8% 3 7% 5% 5% 4 3 6% 7% 38%	2728
	11th to 20th	Night	11% 5% 3 7% 5% 5% 5% 4 6% 7% 41%	2506
	21st to end	Night	16% 8% 2 7% 5% 4 4 4 4 6% 40%	2743
June	1st to 10th	Night	9% 6% 2 6% 4 3 4 4 7% 8% 47%	1520
	11th to 20th	Night	10% 7% 2 5% 4 3 4 4 6% 9% 45%	1520
	21st to end	Night	8% 6% 2 6% 4 3 4 5% 5% 8% 49%	1520
July	1st to 10th	Night	14% 7% 2 6% 4 4 4 4 5% 7% 44%	2530
	11th to 20th	Night	4 3 1 4 4 4 4 4 7% 9% 54%	2530
	21st to end	Night	7% 4 2 6% 4 4 4 4 8% 9% 50%	2750
August	1st to 10th	Night	11% 5% 2 5% 3 3 4 3 6% 9% 48%	2517
	11th to 20th	Night	11% 6% 2 7% 4 4 3 4 5% 7% 46%	2967
	21st to end	Night	8% 5% 1 5% 4 4 5% 4 6% 8% 48%	3476
September	1st to 10th	Night	10% 6% 2 5% 4 4 3 3 5% 7% 53%	1900
	11th to 20th	Night	12% 4 2 5% 3 4 4 3 5% 5% 52%	1980
	21st to end	Night	12% 6% 2 6% 4 4 2 3 4 7% 48%	2090
October	1st to 10th	Night	12% 6% 3 7% 4 3 4 3 5% 6% 48%	2182
	11th to 20th	Night	17% 9% 3 7% 4 4 4 3 4 6% 39%	2306
	21st to end	Night	18% 11% 3 7% 4 4 4 4 6% 7% 34%	2717
November	1st to 10th	Night	13% 8% 3 6% 4 4 3 4 5% 5% 45%	2470
	11th to 20th	Night	13% 12% 4 10% 6% 5% 5% 3 5% 6% 30%	2470
	21st to end	Night	15% 11% 3 8% 5% 5% 4 3 5% 6% 35%	2642
December	1st to 10th	Night	13% 13% 5% 9% 6% 6% 5% 3 6% 6% 28%	2660
	11th to 20th	Night	12% 15% 6% 11% 6% 5% 4 3 5% 4 27%	3279
	21st to end	Night	18% 17% 6% 12% 6% 5% 4 3 4 4 21%	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% 5% 14% 15% 5%	2528
	11th to 20th	Day	63% 6% 10% 16% 4	2530
	21st to end	Day	68% 4 9% 15% 4	2784
February	1st to 10th	Day	53% 6% 11% 20% 9% 1	1710
	11th to 20th	Day	47% 6% 11% 23% 11% 2	1824
	21st to end	Day	53% 5% 11% 18% 10% 3	1570
March	1st to 10th	Day	39% 5% 10% 27% 16% 3	3120
	11th to 20th	Day	39% 7% 11% 27% 15% 2	3275
	21st to end	Day	58% 4 10% 19% 7% 1	4165
April	1st to 10th	Day	52% 6% 12% 20% 10%	2280
	11th to 20th	Day	50% 6% 8% 21% 13% 2	2254
	21st to end	Day	50% 7% 11% 20% 11% 1	2408
May	1st to 10th	Day	42% 6% 11% 23% 16% 1	4206
	11th to 20th	Day	36% 7% 11% 31% 14% 1	4403
	21st to end	Day	40% 8% 11% 23% 16% 2	4837
June	1st to 10th	Day	37% 7% 13% 27% 15% 1	2660
	11th to 20th	Day	39% 6% 13% 25% 15% 1	2660
	21st to end	Day	35% 9% 14% 27% 14% 2	2660
July	1st to 10th	Day	43% 5% 13% 27% 10% 2	4371
	11th to 20th	Day	29% 6% 15% 33% 16% 1	4365
	21st to end	Day	34% 6% 14% 22% 21% 3	4662
August	1st to 10th	Day	38% 5% 14% 28% 12% 1	4408
	11th to 20th	Day	38% 4 11% 35% 11% 1	3897
	21st to end	Day	40% 4 12% 26% 16% 1	4179
September	1st to 10th	Day	38% 6% 12% 27% 16% 1	2280
	11th to 20th	Day	35% 5% 14% 32% 14% 1	2180
	21st to end	Day	42% 5% 11% 30% 11% 1	2090
October	1st to 10th	Day	25% 3 7% 38% 26% 2	3320
	11th to 20th	Day	43% 4 9% 26% 17% 1	3088
	21st to end	Day	44% 3 12% 28% 12% 1	3081
November	1st to 10th	Day	42% 5% 15% 23% 13% 1	1708
	11th to 20th	Day	54% 5% 14% 19% 7% 1	1710
	21st to end	Day	52% 4 15% 22% 7%	1535
December	1st to 10th	Day	58% 6% 14% 15% 6%	1520
	11th to 20th	Day	58% 5% 14% 15% 6% 1	1915
	21st to end	Day	74% 4 8% 10% 4	2783
January	1st to 10th	Night	57% 4 9% 20% 9% 1	4428
	11th to 20th	Night	65% 6% 9% 13% 7%	4440
	21st to end	Night	65% 4 10% 16% 5%	4880
February	1st to 10th	Night	52% 5% 9% 20% 12% 2	2470
	11th to 20th	Night	47% 5% 10% 24% 12% 2	2252
	21st to end	Night	50% 5% 12% 20% 11% 2	1884
March	1st to 10th	Night	42% 6% 12% 27% 10% 3	3733
	11th to 20th	Night	37% 6% 12% 25% 17% 2	3714
	21st to end	Night	56% 4 8% 19% 10% 2	3466
April	1st to 10th	Night	50% 5% 9% 18% 17% 1	1900
	11th to 20th	Night	48% 5% 8% 21% 16% 3	1875
	21st to end	Night	46% 6% 12% 22% 13% 1	1771
May	1st to 10th	Night	44% 6% 13% 20% 16% 2	2755
	11th to 20th	Night	39% 7% 10% 28% 14% 1	2507
	21st to end	Night	44% 6% 10% 19% 15% 6%	2751
June	1st to 10th	Night	32% 7% 14% 28% 17% 1	1520
	11th to 20th	Night	34% 6% 11% 27% 19% 3	1520
	21st to end	Night	33% 7% 15% 26% 16% 3	1520
July	1st to 10th	Night	41% 4 16% 22% 13% 5%	2490
	11th to 20th	Night	25% 5% 17% 34% 17% 2	2482
	21st to end	Night	31% 6% 16% 22% 23% 3	2662
August	1st to 10th	Night	34% 5% 15% 26% 18% 2	2508
	11th to 20th	Night	39% 4 10% 32% 15%	2994
	21st to end	Night	33% 4 14% 26% 20% 3	3476
September	1st to 10th	Night	30% 7% 11% 26% 23% 2	1900
	11th to 20th	Night	33% 4 11% 34% 17% 1	1980
	21st to end	Night	36% 5% 11% 30% 17% 1	2090
October	1st to 10th	Night	28% 3 7% 38% 23% 2	3637
	11th to 20th	Night	35% 3 12% 31% 17% 3	3829
	21st to end	Night	45% 4 10% 26% 16%	4467
November	1st to 10th	Night	40% 5% 11% 25% 16% 2	2470
	11th to 20th	Night	53% 5% 12% 18% 10% 1	2470
	21st to end	Night	49% 5% 16% 23% 7% 1	2642
December	1st to 10th	Night	54% 6% 14% 19% 7% 1	2660
	11th to 20th	Night	60% 5% 11% 16% 8% 1	3281
	21st to end	Night	67% 6% 9% 14% 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	16% 13% 36% 26% 8% 1	270
	11th to 20th	Day	16% 16% 35% 27% 6%	270
	21st to end	Day	20% 11% 37% 26% 5% 1	297
February	1st to 10th	Day	12% 19% 42% 19% 8% 1	270
	11th to 20th	Day	17% 21% 36% 19% 6%	270
	21st to end	Day	18% 18% 46% 15% 2	225
March	1st to 10th	Day	17% 17% 44% 17% 4	270
	11th to 20th	Day	20% 17% 34% 20% 7% 3	279
	21st to end	Day	25% 11% 32% 24% 6% 2	506
April	1st to 10th	Day	25% 13% 34% 23% 5%	460
	11th to 20th	Day	26% 17% 26% 20% 9% 2	452
	21st to end	Day	22% 14% 29% 23% 12% 2	460
May	1st to 10th	Day	20% 13% 32% 25% 9% 2	510
	11th to 20th	Day	17% 10% 33% 24% 13% 3	675
	21st to end	Day	15% 9% 30% 24% 16% 5%	734
June	1st to 10th	Day	11% 9% 31% 30% 16% 4	680
	11th to 20th	Day	13% 8% 33% 26% 15% 5%	680
	21st to end	Day	14% 9% 25% 32% 15% 4	680
July	1st to 10th	Day	8% 5% 21% 31% 25% 10%	671
	11th to 20th	Day	9% 6% 26% 33% 18% 8%	668
	21st to end	Day	7% 4 27% 34% 21% 7%	739
August	1st to 10th	Day	8% 4 23% 35% 21% 9%	676
	11th to 20th	Day	13% 5% 17% 27% 27% 12%	505
	21st to end	Day	14% 7% 21% 29% 21% 9%	539
September	1st to 10th	Day	14% 8% 21% 28% 21% 7%	490
	11th to 20th	Day	11% 5% 21% 34% 20% 9%	490
	21st to end	Day	15% 13% 26% 23% 19% 4	490
October	1st to 10th	Day	19% 12% 27% 25% 13% 4	395
	11th to 20th	Day	21% 18% 33% 20% 8%	300
	21st to end	Day	26% 13% 36% 18% 6% 1	330
November	1st to 10th	Day	19% 14% 33% 24% 9% 2	282
	11th to 20th	Day	16% 18% 39% 21% 7%	270
	21st to end	Day	24% 12% 40% 20% 4	270
December	1st to 10th	Day	17% 19% 41% 17% 5%	270
	11th to 20th	Day	21% 16% 39% 16% 6% 1	270
	21st to end	Day	25% 19% 38% 16% 3	297
January	1st to 10th	Night	16% 15% 38% 23% 7%	950
	11th to 20th	Night	19% 13% 38% 23% 6% 1	950
	21st to end	Night	18% 11% 38% 28% 6%	1045
February	1st to 10th	Night	18% 13% 37% 25% 6%	950
	11th to 20th	Night	14% 16% 38% 25% 7%	776
	21st to end	Night	23% 14% 36% 23% 5%	628
March	1st to 10th	Night	21% 11% 34% 26% 8% 1	760
	11th to 20th	Night	16% 10% 40% 27% 6% 1	722
	21st to end	Night	22% 8% 28% 31% 9% 1	627
April	1st to 10th	Night	23% 11% 37% 23% 6%	570
	11th to 20th	Night	23% 11% 32% 27% 6% 1	563
	21st to end	Night	19% 10% 32% 31% 8% 1	570
May	1st to 10th	Night	18% 10% 36% 29% 7%	570
	11th to 20th	Night	16% 9% 34% 29% 11% 1	561
	21st to end	Night	13% 6% 28% 37% 15% 1	617
June	1st to 10th	Night	11% 5% 30% 39% 15%	570
	11th to 20th	Night	14% 4 33% 36% 12% 1	570
	21st to end	Night	12% 4 26% 41% 16% 1	570
July	1st to 10th	Night	9% 3 18% 42% 27% 2	555
	11th to 20th	Night	8% 3 24% 39% 24% 2	552
	21st to end	Night	8% 1 21% 45% 23% 1	624
August	1st to 10th	Night	10% 2 15% 50% 21% 2	567
	11th to 20th	Night	10% 2 17% 41% 27% 3	564
	21st to end	Night	11% 2 19% 46% 20% 3	627
September	1st to 10th	Night	11% 4 24% 37% 20% 4	570
	11th to 20th	Night	14% 5% 21% 35% 22% 4	650
	21st to end	Night	15% 7% 28% 30% 18% 2	760
October	1st to 10th	Night	16% 8% 29% 31% 16% 1	760
	11th to 20th	Night	22% 12% 34% 26% 7% 1	760
	21st to end	Night	25% 11% 30% 24% 10%	836
November	1st to 10th	Night	17% 12% 35% 26% 8% 1	760
	11th to 20th	Night	19% 16% 38% 21% 5%	760
	21st to end	Night	19% 14% 38% 22% 7%	932
December	1st to 10th	Night	19% 15% 38% 21% 5%	950
	11th to 20th	Night	21% 13% 39% 21% 5% 1	950
	21st to end	Night	24% 15% 36% 22% 3	1045

Page generated at 2024-11-03 01:11:09. Version ac07

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