Fox Run Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Fox Run Observatory clear sky chart from 2005-11-06 to 2024-11-04.

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	15% 11% 4 8% 5% 5% 5% 4 6% 7% 31%	102001
	Night	15% 11% 4 9% 5% 5% 4 4 5% 6% 32%	97002
Transparency	Day	50% 6% 12% 20% 10% 1	105591
	Night	50% 6% 11% 20% 11% 1	101489
Seeing	Day	19% 12% 27% 24% 13% 5%	14901
	Night	19% 11% 30% 28% 11% 1	23875

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	15% 20% 8% 14% 6% 3 4 3 3 5% 20%	2549
	11th to 20th	Day	11% 20% 9% 18% 7% 8% 6% 4 4 3 10%	2840
	21st to end	Day	20% 20% 7% 14% 7% 5% 4 3 3 4 12%	3124
February	1st to 10th	Day	15% 18% 6% 13% 9% 6% 5% 3 4 4 16%	1710
	11th to 20th	Day	14% 12% 7% 15% 7% 4 5% 4 6% 6% 19%	1663
	21st to end	Day	17% 16% 5% 11% 7% 5% 5% 3 6% 5% 21%	1504
March	1st to 10th	Day	21% 15% 5% 9% 5% 4 4 3 4 5% 27%	3399
	11th to 20th	Day	11% 14% 7% 10% 6% 5% 5% 3 5% 5% 28%	3480
	21st to end	Day	16% 12% 4 8% 6% 5% 5% 4 5% 6% 30%	3815
April	1st to 10th	Day	17% 14% 5% 9% 4 5% 4 4 6% 6% 27%	2204
	11th to 20th	Day	20% 10% 3 6% 4 4 4 4 5% 6% 34%	2380
	21st to end	Day	20% 10% 3 7% 5% 4 3 3 6% 6% 32%	2470
May	1st to 10th	Day	18% 9% 3 7% 4 4 4 4 6% 8% 34%	4108
	11th to 20th	Day	16% 9% 3 8% 5% 5% 5% 4 6% 7% 32%	4260
	21st to end	Day	14% 5% 2 5% 4 4 4 3 5% 7% 46%	4837
June	1st to 10th	Day	14% 7% 2 5% 5% 5% 6% 5% 7% 8% 36%	2660
	11th to 20th	Day	11% 6% 2 7% 4 5% 5% 5% 7% 8% 39%	2778
	21st to end	Day	14% 6% 2 6% 5% 4 5% 4 6% 9% 39%	2850
July	1st to 10th	Day	10% 6% 2 6% 5% 5% 5% 5% 8% 10% 38%	4742
	11th to 20th	Day	10% 6% 2 5% 4 4 5% 5% 7% 10% 42%	4345
	21st to end	Day	8% 6% 2 6% 5% 5% 5% 4 7% 9% 42%	4466
August	1st to 10th	Day	15% 7% 2 6% 5% 5% 5% 4 6% 9% 35%	4104
	11th to 20th	Day	11% 8% 3 8% 5% 5% 5% 5% 8% 9% 32%	4044
	21st to end	Day	9% 5% 2 7% 5% 5% 6% 5% 7% 9% 40%	4418
September	1st to 10th	Day	11% 6% 3 6% 5% 5% 5% 4 5% 9% 40%	2280
	11th to 20th	Day	12% 5% 2 6% 4 4 5% 4 6% 10% 43%	2104
	21st to end	Day	14% 8% 3 7% 4 6% 5% 4 7% 9% 34%	2090
October	1st to 10th	Day	18% 10% 3 7% 4 5% 5% 4 6% 6% 32%	1900
	11th to 20th	Day	22% 9% 3 9% 4 5% 3 4 5% 7% 29%	1900
	21st to end	Day	24% 13% 4 8% 5% 5% 5% 4 5% 7% 20%	2089
November	1st to 10th	Day	15% 12% 4 9% 5% 4 5% 4 6% 7% 29%	1650
	11th to 20th	Day	15% 15% 4 9% 7% 4 6% 5% 6% 6% 24%	1520
	21st to end	Day	18% 16% 7% 12% 5% 4 4 3 6% 6% 18%	1520
December	1st to 10th	Day	14% 21% 7% 13% 6% 5% 4 4 5% 6% 14%	1520
	11th to 20th	Day	18% 20% 6% 11% 6% 6% 6% 4 4 5% 17%	1906
	21st to end	Day	28% 19% 6% 14% 6% 5% 4 3 3 3 8%	2772
January	1st to 10th	Night	17% 18% 8% 14% 6% 5% 4 4 5% 5% 15%	4393
	11th to 20th	Night	14% 15% 8% 16% 10% 8% 7% 4 5% 4 9%	4120
	21st to end	Night	21% 15% 9% 12% 5% 5% 4 3 4 5% 17%	4532
February	1st to 10th	Night	14% 16% 5% 10% 9% 6% 5% 4 6% 6% 19%	2470
	11th to 20th	Night	14% 13% 6% 11% 7% 5% 5% 4 6% 7% 23%	2403
	21st to end	Night	15% 12% 5% 12% 5% 5% 4 3 6% 7% 25%	1946
March	1st to 10th	Night	15% 10% 4 9% 5% 5% 4 4 5% 6% 32%	3440
	11th to 20th	Night	11% 10% 4 9% 4 4 4 4 6% 7% 36%	3479
	21st to end	Night	16% 9% 3 7% 4 4 4 3 5% 5% 39%	3817
April	1st to 10th	Night	19% 11% 3 7% 6% 4 4 4 4 6% 31%	1976
	11th to 20th	Night	16% 10% 3 7% 5% 3 4 4 5% 5% 37%	1763
	21st to end	Night	15% 8% 3 8% 5% 5% 4 3 6% 7% 35%	1710
May	1st to 10th	Night	16% 8% 2 6% 4 3 4 3 6% 7% 41%	2833
	11th to 20th	Night	13% 9% 3 8% 5% 4 5% 3 6% 7% 36%	2633
	21st to end	Night	9% 5% 1 5% 4 4 4 3 5% 9% 51%	2738
June	1st to 10th	Night	12% 6% 2 5% 4 6% 4 4 7% 8% 43%	1520
	11th to 20th	Night	10% 5% 2 6% 4 5% 5% 4 8% 9% 42%	1396
	21st to end	Night	12% 5% 2 6% 5% 5% 4 3 5% 7% 46%	1330
July	1st to 10th	Night	6% 4 2 5% 3 3 4 4 6% 9% 53%	2210
	11th to 20th	Night	10% 5% 2 5% 3 4 3 3 4 8% 53%	2611
	21st to end	Night	6% 5% 2 6% 4 5% 5% 4 6% 8% 49%	3087
August	1st to 10th	Night	11% 6% 3 6% 4 4 4 4 6% 7% 46%	2825
	11th to 20th	Night	11% 6% 2 6% 4 4 4 4 6% 9% 45%	2785
	21st to end	Night	11% 5% 2 6% 3 4 4 4 5% 8% 48%	3206
September	1st to 10th	Night	9% 5% 2 7% 4 4 5% 3 6% 7% 47%	1900
	11th to 20th	Night	11% 5% 2 4 3 3 3 4 6% 7% 53%	2071
	21st to end	Night	16% 7% 3 7% 4 5% 3 3 5% 7% 41%	2090
October	1st to 10th	Night	15% 7% 2 9% 5% 5% 4 3 5% 6% 40%	2280
	11th to 20th	Night	18% 9% 3 7% 5% 4 5% 3 4 6% 34%	2280
	21st to end	Night	20% 10% 3 8% 6% 5% 4 4 6% 7% 27%	2508
November	1st to 10th	Night	14% 10% 3 7% 5% 5% 4 4 6% 7% 34%	2498
	11th to 20th	Night	15% 13% 3 10% 6% 5% 5% 4 6% 8% 25%	2660
	21st to end	Night	18% 14% 4 9% 7% 4 5% 3 6% 8% 23%	2660
December	1st to 10th	Night	19% 17% 6% 12% 6% 5% 5% 4 5% 5% 16%	2660
	11th to 20th	Night	16% 18% 7% 12% 6% 5% 5% 4 5% 5% 19%	3288
	21st to end	Night	26% 21% 7% 12% 6% 5% 4 3 4 4 9%	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% 6% 9% 10% 8%	2550
	11th to 20th	Day	75% 10% 5% 6% 4	2840
	21st to end	Day	76% 5% 6% 7% 5%	3124
February	1st to 10th	Day	70% 6% 8% 12% 4 1	1710
	11th to 20th	Day	64% 6% 7% 14% 7% 2	1672
	21st to end	Day	65% 4 9% 14% 7% 1	1504
March	1st to 10th	Day	61% 4 10% 17% 7% 1	3402
	11th to 20th	Day	57% 5% 11% 19% 7% 2	3480
	21st to end	Day	53% 7% 9% 19% 10% 2	3815
April	1st to 10th	Day	56% 6% 10% 18% 10%	2204
	11th to 20th	Day	50% 5% 11% 20% 13% 1	2380
	21st to end	Day	53% 5% 10% 19% 11% 2	2470
May	1st to 10th	Day	47% 5% 13% 20% 12% 2	4120
	11th to 20th	Day	49% 8% 15% 20% 7% 1	4264
	21st to end	Day	37% 5% 14% 22% 18% 5%	4837
June	1st to 10th	Day	43% 8% 12% 21% 15% 1	2660
	11th to 20th	Day	38% 7% 14% 24% 15% 1	2778
	21st to end	Day	41% 7% 12% 25% 14%	2850
July	1st to 10th	Day	38% 6% 17% 23% 15% 2	4668
	11th to 20th	Day	34% 7% 14% 34% 11% 1	4270
	21st to end	Day	36% 7% 14% 22% 19% 1	4324
August	1st to 10th	Day	43% 7% 14% 23% 13% 1	4091
	11th to 20th	Day	44% 8% 16% 24% 9%	4083
	21st to end	Day	37% 7% 13% 31% 10% 1	4418
September	1st to 10th	Day	40% 7% 15% 26% 11% 1	2280
	11th to 20th	Day	35% 7% 14% 29% 14% 1	2104
	21st to end	Day	46% 6% 14% 24% 9%	2090
October	1st to 10th	Day	43% 7% 13% 22% 14% 1	3160
	11th to 20th	Day	43% 6% 13% 21% 17%	3140
	21st to end	Day	53% 6% 15% 19% 7%	3415
November	1st to 10th	Day	53% 7% 11% 20% 8% 1	1650
	11th to 20th	Day	58% 7% 12% 14% 7% 1	1520
	21st to end	Day	67% 5% 10% 12% 5%	1520
December	1st to 10th	Day	72% 6% 9% 9% 4	1520
	11th to 20th	Day	69% 7% 10% 9% 6%	1906
	21st to end	Day	82% 6% 5% 6% 2	2772
January	1st to 10th	Night	69% 8% 8% 11% 4 1	4393
	11th to 20th	Night	75% 7% 7% 7% 3	4120
	21st to end	Night	70% 5% 9% 12% 4 1	4532
February	1st to 10th	Night	65% 6% 8% 16% 4 1	2470
	11th to 20th	Night	59% 6% 10% 16% 9% 1	2405
	21st to end	Night	59% 5% 11% 17% 8%	1946
March	1st to 10th	Night	51% 5% 15% 20% 7% 1	3450
	11th to 20th	Night	45% 7% 14% 20% 13% 2	3480
	21st to end	Night	46% 6% 7% 22% 17% 2	3817
April	1st to 10th	Night	54% 4 8% 19% 15% 1	1976
	11th to 20th	Night	47% 5% 8% 22% 16% 2	1763
	21st to end	Night	47% 5% 9% 21% 15% 2	1710
May	1st to 10th	Night	43% 5% 12% 19% 16% 5%	2840
	11th to 20th	Night	45% 7% 16% 20% 11% 2	2634
	21st to end	Night	31% 6% 14% 23% 22% 3	2739
June	1st to 10th	Night	38% 7% 12% 26% 17% 1	1520
	11th to 20th	Night	35% 6% 13% 26% 18% 2	1396
	21st to end	Night	36% 6% 14% 25% 17% 1	1330
July	1st to 10th	Night	28% 5% 14% 26% 21% 5%	2175
	11th to 20th	Night	31% 5% 12% 34% 18% 1	2563
	21st to end	Night	32% 8% 13% 28% 17% 2	2988
August	1st to 10th	Night	36% 6% 13% 26% 16% 2	2814
	11th to 20th	Night	36% 7% 16% 28% 13% 1	2812
	21st to end	Night	33% 7% 11% 33% 15% 1	3206
September	1st to 10th	Night	35% 8% 13% 28% 15% 1	1900
	11th to 20th	Night	29% 6% 12% 31% 20% 1	2071
	21st to end	Night	43% 5% 13% 27% 12%	2090
October	1st to 10th	Night	34% 5% 10% 27% 23% 1	3800
	11th to 20th	Night	45% 5% 12% 24% 15%	3779
	21st to end	Night	43% 5% 17% 26% 9%	4120
November	1st to 10th	Night	46% 8% 12% 21% 12% 1	2498
	11th to 20th	Night	56% 7% 12% 17% 7% 1	2660
	21st to end	Night	59% 6% 16% 13% 5% 1	2660
December	1st to 10th	Night	69% 7% 10% 11% 3	2660
	11th to 20th	Night	66% 5% 11% 13% 4	3288
	21st to end	Night	80% 4 7% 6% 2	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	24% 19% 31% 18% 8% 1	189
	11th to 20th	Day	22% 17% 41% 16% 3 1	270
	21st to end	Day	26% 18% 32% 20% 5%	297
February	1st to 10th	Day	24% 21% 38% 13% 4	270
	11th to 20th	Day	21% 22% 37% 17% 2	270
	21st to end	Day	26% 29% 30% 14% 1	225
March	1st to 10th	Day	24% 14% 34% 21% 6%	438
	11th to 20th	Day	20% 16% 35% 20% 7% 1	460
	21st to end	Day	29% 12% 31% 21% 6% 1	506
April	1st to 10th	Day	20% 19% 31% 22% 7% 1	460
	11th to 20th	Day	28% 17% 25% 17% 10% 4	452
	21st to end	Day	25% 13% 30% 22% 9% 2	460
May	1st to 10th	Day	22% 12% 25% 27% 11% 4	463
	11th to 20th	Day	16% 10% 27% 24% 16% 6%	487
	21st to end	Day	14% 6% 28% 28% 16% 8%	529
June	1st to 10th	Day	14% 11% 28% 29% 15% 3	490
	11th to 20th	Day	13% 9% 26% 31% 17% 4	608
	21st to end	Day	15% 9% 27% 33% 12% 3	680
July	1st to 10th	Day	9% 7% 23% 31% 22% 9%	666
	11th to 20th	Day	13% 6% 23% 26% 23% 9%	484
	21st to end	Day	10% 4 23% 33% 20% 10%	532
August	1st to 10th	Day	12% 6% 20% 28% 22% 12%	486
	11th to 20th	Day	11% 6% 19% 25% 23% 15%	479
	21st to end	Day	14% 6% 21% 27% 21% 12%	539
September	1st to 10th	Day	10% 10% 23% 24% 19% 13%	490
	11th to 20th	Day	11% 5% 18% 25% 25% 16%	490
	21st to end	Day	17% 12% 22% 24% 18% 7%	490
October	1st to 10th	Day	21% 12% 25% 22% 13% 8%	490
	11th to 20th	Day	21% 15% 32% 22% 8% 2	490
	21st to end	Day	29% 14% 28% 22% 6% 1	538
November	1st to 10th	Day	20% 21% 30% 20% 7% 2	255
	11th to 20th	Day	26% 15% 33% 18% 4 3	180
	21st to end	Day	27% 17% 33% 18% 4	180
December	1st to 10th	Day	29% 18% 31% 16% 6%	180
	11th to 20th	Day	29% 23% 26% 17% 4 1	180
	21st to end	Day	28% 22% 36% 12% 2	198
January	1st to 10th	Night	23% 19% 35% 17% 6% 1	760
	11th to 20th	Night	27% 17% 31% 20% 4	760
	21st to end	Night	21% 12% 37% 22% 7%	836
February	1st to 10th	Night	23% 18% 35% 22% 2	760
	11th to 20th	Night	22% 16% 36% 21% 4	743
	21st to end	Night	21% 18% 36% 21% 3	628
March	1st to 10th	Night	18% 16% 37% 24% 6%	760
	11th to 20th	Night	19% 17% 38% 20% 7%	760
	21st to end	Night	22% 12% 33% 24% 8% 1	836
April	1st to 10th	Night	22% 17% 31% 25% 5%	760
	11th to 20th	Night	21% 12% 33% 23% 9% 2	639
	21st to end	Night	17% 12% 31% 31% 8%	570
May	1st to 10th	Night	16% 7% 32% 29% 14% 1	570
	11th to 20th	Night	16% 5% 28% 38% 12% 1	460
	21st to end	Night	11% 4 29% 37% 19%	411
June	1st to 10th	Night	14% 5% 29% 40% 12%	380
	11th to 20th	Night	12% 6% 29% 39% 13%	380
	21st to end	Night	12% 6% 24% 42% 16% 1	380
July	1st to 10th	Night	6% 4 20% 48% 21% 1	370
	11th to 20th	Night	8% 4 25% 38% 24% 2	420
	21st to end	Night	10% 3 19% 46% 21% 1	624
August	1st to 10th	Night	8% 2 19% 42% 26% 3	567
	11th to 20th	Night	9% 4 16% 39% 29% 4	564
	21st to end	Night	14% 3 21% 33% 27% 2	670
September	1st to 10th	Night	11% 6% 21% 36% 21% 5%	760
	11th to 20th	Night	12% 5% 19% 32% 27% 5%	760
	21st to end	Night	19% 7% 20% 30% 19% 5%	760
October	1st to 10th	Night	18% 7% 28% 29% 15% 3	760
	11th to 20th	Night	22% 11% 28% 29% 9% 2	760
	21st to end	Night	25% 13% 30% 25% 6%	836
November	1st to 10th	Night	21% 12% 28% 29% 9% 1	755
	11th to 20th	Night	22% 15% 34% 21% 8% 1	760
	21st to end	Night	25% 14% 33% 22% 5%	760
December	1st to 10th	Night	28% 17% 31% 19% 4	760
	11th to 20th	Night	23% 19% 36% 16% 4	760
	21st to end	Night	30% 16% 33% 18% 3	836

Page generated at 2024-11-01 22:47:49. Version ac07

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