Fox Park Public Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Fox Park Public Observatory 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% 10% 3 8% 5% 5% 5% 4 6% 7% 34%	101216
	Night	14% 11% 4 9% 5% 4 4 3 5% 6% 34%	97881
Transparency	Day	47% 6% 12% 21% 12% 1	104816
	Night	49% 6% 11% 21% 12% 1	102421
Seeing	Day	17% 11% 28% 24% 14% 6%	15767
	Night	19% 9% 30% 29% 12% 1	25606

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	16% 19% 6% 10% 7% 6% 5% 4 4 5% 19%	2527
	11th to 20th	Day	15% 18% 7% 14% 9% 11% 4 3 5% 4 9%	2530
	21st to end	Day	26% 22% 7% 11% 6% 4 3 1 2 4 14%	2857
February	1st to 10th	Day	13% 15% 5% 13% 9% 6% 4 4 4 6% 20%	1729
	11th to 20th	Day	13% 13% 6% 14% 9% 5% 4 2 3 5% 26%	1848
	21st to end	Day	14% 16% 4 12% 6% 5% 5% 4 4 5% 25%	1570
March	1st to 10th	Day	15% 15% 4 8% 5% 4 4 3 5% 7% 30%	3120
	11th to 20th	Day	11% 11% 4 10% 7% 5% 5% 4 6% 7% 31%	3447
	21st to end	Day	18% 14% 4 9% 5% 5% 4 3 5% 5% 28%	3861
April	1st to 10th	Day	17% 14% 4 8% 5% 5% 4 4 5% 6% 30%	2280
	11th to 20th	Day	17% 10% 3 7% 4 5% 4 3 4 7% 36%	2347
	21st to end	Day	16% 9% 3 8% 5% 5% 5% 3 4 7% 34%	2470
May	1st to 10th	Day	17% 8% 3 7% 4 5% 4 3 6% 7% 36%	4082
	11th to 20th	Day	15% 8% 2 6% 4 4 4 4 6% 9% 37%	4081
	21st to end	Day	11% 7% 2 6% 4 4 4 3 6% 8% 45%	4684
June	1st to 10th	Day	10% 5% 2 6% 5% 5% 5% 5% 6% 8% 43%	2660
	11th to 20th	Day	10% 5% 2 7% 6% 4 4 4 6% 9% 43%	2660
	21st to end	Day	9% 6% 2 7% 6% 5% 5% 5% 8% 8% 39%	2660
July	1st to 10th	Day	11% 6% 2 7% 5% 5% 6% 5% 8% 9% 36%	4440
	11th to 20th	Day	7% 5% 2 4 4 4 5% 4 7% 10% 49%	4440
	21st to end	Day	5% 6% 2 7% 5% 5% 6% 5% 7% 9% 44%	4730
August	1st to 10th	Day	12% 5% 2 5% 5% 4 5% 5% 6% 9% 42%	4104
	11th to 20th	Day	11% 6% 2 6% 5% 4 5% 3 6% 8% 44%	4044
	21st to end	Day	7% 6% 2 7% 5% 5% 5% 5% 7% 9% 42%	4322
September	1st to 10th	Day	11% 6% 2 6% 5% 5% 5% 4 6% 7% 42%	2209
	11th to 20th	Day	11% 5% 2 5% 4 3 4 3 6% 7% 49%	2090
	21st to end	Day	13% 7% 3 7% 5% 5% 5% 4 6% 8% 37%	2090
October	1st to 10th	Day	14% 7% 3 7% 4 5% 4 4 5% 7% 42%	2090
	11th to 20th	Day	17% 9% 4 9% 5% 4 5% 3 6% 6% 31%	1876
	21st to end	Day	21% 12% 3 7% 5% 5% 4 3 5% 7% 26%	1881
November	1st to 10th	Day	12% 12% 3 6% 5% 5% 4 4 4 6% 39%	1708
	11th to 20th	Day	14% 15% 5% 9% 7% 5% 4 3 6% 6% 26%	1710
	21st to end	Day	18% 16% 5% 9% 5% 4 3 3 5% 5% 28%	1710
December	1st to 10th	Day	13% 18% 8% 13% 7% 5% 4 4 4 4 19%	1658
	11th to 20th	Day	14% 18% 6% 12% 6% 6% 5% 4 5% 5% 19%	1918
	21st to end	Day	21% 23% 8% 14% 5% 4 4 3 4 4 11%	2783
January	1st to 10th	Night	16% 18% 8% 13% 7% 4 4 3 4 5% 19%	4428
	11th to 20th	Night	14% 18% 8% 16% 7% 9% 4 3 4 4 13%	4440
	21st to end	Night	22% 18% 9% 13% 5% 4 4 2 4 4 14%	4806
February	1st to 10th	Night	15% 17% 4 11% 9% 6% 5% 3 4 4 21%	2447
	11th to 20th	Night	12% 13% 5% 12% 7% 6% 5% 4 5% 5% 26%	2218
	21st to end	Night	17% 12% 4 11% 5% 4 5% 4 6% 6% 27%	1884
March	1st to 10th	Night	14% 10% 5% 8% 5% 4 4 3 4 7% 37%	3733
	11th to 20th	Night	9% 9% 2 7% 4 4 5% 4 5% 8% 44%	3512
	21st to end	Night	17% 11% 5% 10% 5% 4 4 3 4 6% 32%	3800
April	1st to 10th	Night	15% 12% 3 6% 5% 5% 4 4 5% 6% 36%	1900
	11th to 20th	Night	19% 8% 3 6% 4 3 4 3 5% 6% 37%	1782
	21st to end	Night	18% 7% 4 5% 5% 5% 4 4 5% 8% 37%	1710
May	1st to 10th	Night	14% 8% 3 8% 5% 4 5% 4 6% 8% 35%	2813
	11th to 20th	Night	16% 8% 3 6% 4 4 3 3 5% 7% 42%	2812
	21st to end	Night	11% 6% 2 6% 4 5% 4 4 6% 8% 44%	2874
June	1st to 10th	Night	12% 5% 1 5% 4 4 4 4 6% 8% 46%	1520
	11th to 20th	Night	10% 5% 3 5% 4 4 4 3 7% 8% 45%	1520
	21st to end	Night	9% 5% 2 6% 4 4 4 4 6% 9% 46%	1520
July	1st to 10th	Night	8% 5% 1 5% 4 4 5% 5% 8% 10% 44%	2530
	11th to 20th	Night	8% 4 2 5% 4 3 3 4 5% 8% 55%	2530
	21st to end	Night	5% 5% 3 7% 5% 4 4 5% 7% 9% 46%	2831
August	1st to 10th	Night	9% 6% 2 5% 4 4 4 3 6% 9% 47%	2825
	11th to 20th	Night	11% 6% 2 5% 5% 4 4 4 6% 7% 46%	2785
	21st to end	Night	8% 7% 3 7% 5% 4 4 3 6% 8% 45%	3332
September	1st to 10th	Night	9% 5% 1 6% 5% 4 4 4 5% 8% 49%	1952
	11th to 20th	Night	10% 5% 2 4 4 3 4 3 4 7% 55%	2090
	21st to end	Night	14% 7% 3 7% 5% 4 4 3 4 7% 43%	2090
October	1st to 10th	Night	15% 6% 3 5% 3 3 3 3 5% 7% 45%	2090
	11th to 20th	Night	18% 11% 3 7% 5% 5% 4 3 5% 5% 33%	2299
	21st to end	Night	21% 10% 3 8% 5% 4 4 3 5% 6% 31%	2717
November	1st to 10th	Night	14% 11% 3 7% 4 4 3 3 5% 5% 41%	2470
	11th to 20th	Night	14% 14% 4 9% 5% 5% 6% 4 5% 7% 27%	2470
	21st to end	Night	17% 15% 4 8% 4 4 4 4 5% 6% 28%	2470
December	1st to 10th	Night	16% 18% 7% 12% 7% 4 5% 4 5% 5% 18%	2518
	11th to 20th	Night	14% 17% 6% 14% 6% 5% 4 3 4 5% 20%	3279
	21st to end	Night	25% 22% 6% 11% 5% 5% 4 3 4 5% 12%	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	67% 7% 10% 13% 2	2528
	11th to 20th	Day	78% 6% 8% 6% 2	2530
	21st to end	Day	77% 4 9% 7% 2	2857
February	1st to 10th	Day	64% 7% 10% 13% 6%	1729
	11th to 20th	Day	62% 4 9% 15% 9% 1	1858
	21st to end	Day	62% 5% 11% 14% 6% 2	1570
March	1st to 10th	Day	54% 6% 12% 19% 7% 1	3120
	11th to 20th	Day	50% 6% 15% 19% 8% 1	3447
	21st to end	Day	58% 6% 10% 15% 9% 2	3861
April	1st to 10th	Day	55% 4 11% 19% 10%	2280
	11th to 20th	Day	49% 5% 11% 20% 14% 2	2347
	21st to end	Day	48% 6% 11% 17% 14% 2	2470
May	1st to 10th	Day	46% 6% 12% 21% 13% 1	4120
	11th to 20th	Day	42% 9% 14% 25% 10% 1	4085
	21st to end	Day	36% 8% 11% 20% 23% 3	4697
June	1st to 10th	Day	37% 7% 13% 26% 16% 2	2660
	11th to 20th	Day	37% 7% 13% 23% 19% 2	2660
	21st to end	Day	39% 8% 13% 22% 16% 2	2660
July	1st to 10th	Day	42% 7% 14% 20% 15% 3	4371
	11th to 20th	Day	28% 6% 14% 32% 18% 2	4365
	21st to end	Day	34% 7% 16% 20% 21% 2	4580
August	1st to 10th	Day	37% 7% 13% 26% 16% 1	4091
	11th to 20th	Day	37% 6% 11% 31% 13% 1	4083
	21st to end	Day	36% 7% 13% 30% 13% 2	4321
September	1st to 10th	Day	39% 7% 13% 24% 16% 2	2209
	11th to 20th	Day	33% 5% 12% 30% 18% 1	2090
	21st to end	Day	43% 6% 12% 23% 15%	2090
October	1st to 10th	Day	30% 4 9% 36% 20% 1	3480
	11th to 20th	Day	41% 5% 10% 26% 17%	3092
	21st to end	Day	49% 5% 11% 24% 10% 1	3081
November	1st to 10th	Day	44% 7% 13% 21% 14% 1	1708
	11th to 20th	Day	58% 6% 11% 17% 7% 1	1710
	21st to end	Day	59% 5% 14% 16% 6% 1	1710
December	1st to 10th	Day	68% 6% 11% 11% 3	1658
	11th to 20th	Day	66% 7% 12% 12% 3	1915
	21st to end	Day	78% 5% 8% 6% 3	2783
January	1st to 10th	Night	67% 7% 10% 12% 5% 1	4428
	11th to 20th	Night	75% 5% 9% 7% 4	4440
	21st to end	Night	75% 5% 8% 9% 3	4806
February	1st to 10th	Night	65% 6% 10% 13% 6% 1	2447
	11th to 20th	Night	59% 6% 9% 16% 9% 1	2219
	21st to end	Night	57% 6% 12% 16% 8% 2	1884
March	1st to 10th	Night	48% 6% 14% 25% 7% 1	3733
	11th to 20th	Night	35% 7% 16% 21% 19% 1	3512
	21st to end	Night	52% 6% 11% 20% 9% 1	3800
April	1st to 10th	Night	47% 6% 11% 21% 13% 1	1900
	11th to 20th	Night	46% 6% 11% 18% 17% 2	1782
	21st to end	Night	45% 5% 13% 20% 13% 3	1710
May	1st to 10th	Night	44% 8% 12% 21% 14% 2	2840
	11th to 20th	Night	41% 6% 9% 24% 16% 2	2813
	21st to end	Night	36% 7% 12% 22% 20% 3	2882
June	1st to 10th	Night	33% 6% 13% 28% 17% 2	1520
	11th to 20th	Night	35% 7% 14% 25% 17% 2	1520
	21st to end	Night	33% 8% 14% 25% 18% 2	1520
July	1st to 10th	Night	32% 6% 13% 28% 14% 7%	2490
	11th to 20th	Night	27% 5% 13% 32% 22% 1	2482
	21st to end	Night	33% 8% 17% 17% 24% 3	2741
August	1st to 10th	Night	33% 6% 13% 29% 18% 1	2814
	11th to 20th	Night	35% 6% 10% 32% 14% 1	2812
	21st to end	Night	36% 6% 11% 29% 16% 2	3332
September	1st to 10th	Night	33% 7% 11% 27% 20% 2	1952
	11th to 20th	Night	29% 5% 10% 32% 22% 2	2090
	21st to end	Night	41% 7% 12% 25% 15% 1	2090
October	1st to 10th	Night	27% 4 10% 36% 23% 1	3480
	11th to 20th	Night	45% 4 10% 21% 20%	3822
	21st to end	Night	41% 4 10% 30% 14% 1	4467
November	1st to 10th	Night	45% 6% 11% 24% 14% 1	2470
	11th to 20th	Night	54% 7% 13% 18% 7% 1	2470
	21st to end	Night	56% 6% 13% 19% 5%	2470
December	1st to 10th	Night	67% 7% 10% 11% 5%	2518
	11th to 20th	Night	66% 5% 12% 11% 5%	3281
	21st to end	Night	75% 6% 10% 7% 3	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	23% 15% 35% 19% 7% 1	270
	11th to 20th	Day	22% 15% 41% 16% 5% 1	270
	21st to end	Day	28% 14% 34% 19% 4	297
February	1st to 10th	Day	23% 20% 33% 19% 3 1	270
	11th to 20th	Day	23% 18% 39% 18% 2	270
	21st to end	Day	26% 25% 33% 13% 2	225
March	1st to 10th	Day	20% 19% 44% 12% 4	270
	11th to 20th	Day	22% 15% 32% 24% 7%	440
	21st to end	Day	26% 15% 29% 24% 5% 2	506
April	1st to 10th	Day	22% 13% 34% 23% 6% 1	460
	11th to 20th	Day	26% 17% 29% 17% 7% 5%	452
	21st to end	Day	20% 15% 32% 22% 11% 2	460
May	1st to 10th	Day	23% 14% 25% 25% 10% 3	463
	11th to 20th	Day	18% 11% 26% 24% 15% 6%	487
	21st to end	Day	15% 7% 25% 27% 19% 7%	646
June	1st to 10th	Day	12% 9% 27% 32% 16% 5%	680
	11th to 20th	Day	13% 6% 29% 31% 16% 5%	680
	21st to end	Day	12% 8% 29% 30% 16% 6%	680
July	1st to 10th	Day	8% 5% 20% 31% 22% 14%	671
	11th to 20th	Day	11% 6% 24% 28% 22% 9%	668
	21st to end	Day	8% 4 23% 32% 23% 9%	692
August	1st to 10th	Day	9% 4 19% 27% 21% 20%	486
	11th to 20th	Day	14% 4 14% 29% 29% 10%	479
	21st to end	Day	11% 4 21% 27% 25% 12%	539
September	1st to 10th	Day	14% 6% 22% 24% 23% 11%	490
	11th to 20th	Day	10% 5% 16% 23% 29% 15%	490
	21st to end	Day	17% 12% 20% 24% 18% 10%	490
October	1st to 10th	Day	18% 8% 28% 23% 16% 7%	490
	11th to 20th	Day	20% 17% 26% 27% 9% 1	457
	21st to end	Day	27% 16% 34% 17% 4 1	330
November	1st to 10th	Day	16% 17% 35% 24% 7% 1	282
	11th to 20th	Day	24% 20% 34% 17% 5%	270
	21st to end	Day	29% 16% 38% 12% 6%	270
December	1st to 10th	Day	24% 25% 30% 13% 7%	270
	11th to 20th	Day	22% 20% 41% 13% 4	270
	21st to end	Day	25% 22% 35% 14% 3	297
January	1st to 10th	Night	21% 14% 35% 22% 6% 1	950
	11th to 20th	Night	24% 14% 34% 23% 5% 1	950
	21st to end	Night	20% 11% 35% 29% 5%	993
February	1st to 10th	Night	24% 12% 37% 23% 3	760
	11th to 20th	Night	20% 15% 36% 25% 3	743
	21st to end	Night	23% 14% 40% 19% 3	628
March	1st to 10th	Night	20% 12% 35% 26% 7% 1	760
	11th to 20th	Night	17% 13% 38% 26% 6% 1	760
	21st to end	Night	22% 10% 33% 26% 8%	831
April	1st to 10th	Night	18% 12% 39% 25% 5% 1	570
	11th to 20th	Night	23% 10% 35% 23% 8% 1	563
	21st to end	Night	22% 6% 34% 29% 8% 1	570
May	1st to 10th	Night	20% 6% 32% 32% 9% 1	570
	11th to 20th	Night	21% 6% 31% 30% 11% 1	561
	21st to end	Night	12% 3 27% 35% 21% 2	617
June	1st to 10th	Night	13% 3 25% 44% 15% 1	570
	11th to 20th	Night	13% 4 25% 39% 18% 1	570
	21st to end	Night	10% 5% 22% 41% 21% 1	570
July	1st to 10th	Night	8% 2 18% 41% 27% 5%	555
	11th to 20th	Night	11% 2 18% 41% 25% 3	552
	21st to end	Night	6% 2 18% 47% 25% 2	624
August	1st to 10th	Night	9% 1 16% 43% 28% 3	567
	11th to 20th	Night	9% 1 17% 39% 29% 5%	564
	21st to end	Night	11% 3 18% 37% 28% 3	627
September	1st to 10th	Night	10% 4 19% 38% 25% 4	622
	11th to 20th	Night	12% 4 15% 36% 28% 4	760
	21st to end	Night	18% 6% 23% 28% 21% 5%	760
October	1st to 10th	Night	18% 6% 25% 32% 18% 1	760
	11th to 20th	Night	22% 12% 29% 28% 8% 1	760
	21st to end	Night	25% 11% 33% 24% 7%	836
November	1st to 10th	Night	20% 10% 30% 30% 9% 1	760
	11th to 20th	Night	21% 14% 35% 23% 6% 1	760
	21st to end	Night	24% 12% 34% 26% 4	760
December	1st to 10th	Night	24% 15% 34% 21% 6%	808
	11th to 20th	Night	23% 14% 36% 23% 4	950
	21st to end	Night	31% 12% 34% 21% 1	1045

Page generated at 2024-11-03 02:11:25. Version ac07

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