Paxton Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Paxton Park clear sky chart from 2005-11-06 to 2025-01-22.

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% 7% 2 6% 4 4 4 4 6% 7% 42%	104881
	Night	14% 7% 2 6% 4 4 4 3 5% 7% 45%	104529
Transparency	Day	38% 6% 11% 24% 18% 3	108541
	Night	37% 5% 10% 24% 19% 4	108998
Seeing	Day	15% 7% 21% 26% 20% 10%	15684
	Night	17% 6% 24% 32% 19% 3	25580

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	15% 10% 4 9% 5% 4 4 3 5% 5% 37%	2607
	11th to 20th	Day	18% 8% 3 5% 4 4 4 3 4 5% 41%	2714
	21st to end	Day	24% 11% 4 9% 4 4 4 3 4 5% 30%	3144
February	1st to 10th	Day	18% 11% 3 6% 5% 3 3 3 6% 6% 36%	1883
	11th to 20th	Day	18% 10% 4 7% 4 4 4 3 4 5% 39%	1848
	21st to end	Day	18% 9% 4 8% 5% 4 4 2 4 6% 35%	1570
March	1st to 10th	Day	19% 13% 3 7% 4 4 3 3 4 5% 34%	3120
	11th to 20th	Day	14% 7% 2 5% 3 3 3 2 4 6% 50%	3306
	21st to end	Day	12% 8% 3 7% 5% 4 5% 3 6% 6% 42%	4164
April	1st to 10th	Day	13% 6% 2 6% 3 4 4 4 5% 8% 45%	2280
	11th to 20th	Day	13% 9% 2 8% 5% 4 4 4 5% 6% 41%	2254
	21st to end	Day	17% 7% 3 6% 4 4 4 4 5% 7% 40%	2280
May	1st to 10th	Day	15% 8% 2 7% 4 5% 5% 5% 7% 10% 32%	3983
	11th to 20th	Day	17% 7% 2 7% 4 4 5% 4 5% 8% 37%	4081
	21st to end	Day	11% 6% 2 7% 5% 5% 5% 4 7% 8% 40%	4682
June	1st to 10th	Day	9% 5% 1 5% 4 5% 6% 4 8% 9% 44%	2660
	11th to 20th	Day	5% 3 2 5% 5% 4 5% 5% 6% 10% 49%	2660
	21st to end	Day	5% 5% 2 5% 5% 5% 6% 5% 8% 10% 45%	2660
July	1st to 10th	Day	9% 5% 2 6% 5% 5% 6% 5% 7% 10% 40%	4440
	11th to 20th	Day	6% 3 1 5% 4 4 5% 4 7% 10% 49%	4440
	21st to end	Day	9% 9% 4 9% 7% 6% 6% 5% 7% 9% 31%	4685
August	1st to 10th	Day	5% 4 1 4 3 4 4 4 6% 10% 55%	3785
	11th to 20th	Day	9% 5% 2 6% 5% 4 5% 4 7% 10% 43%	3729
	21st to end	Day	5% 3 1 5% 4 4 4 4 6% 8% 56%	4180
September	1st to 10th	Day	10% 6% 2 5% 4 4 4 4 6% 8% 47%	2280
	11th to 20th	Day	10% 6% 2 5% 4 5% 4 4 5% 7% 48%	2161
	21st to end	Day	12% 5% 2 4 4 3 5% 3 4 7% 50%	2090
October	1st to 10th	Day	9% 4 2 5% 3 3 4 2 4 6% 59%	2065
	11th to 20th	Day	13% 5% 2 5% 4 3 3 2 4 6% 52%	1900
	21st to end	Day	19% 6% 2 4 3 3 3 3 4 5% 47%	1993
November	1st to 10th	Day	11% 5% 2 6% 3 4 4 3 5% 6% 52%	1762
	11th to 20th	Day	14% 8% 2 6% 4 3 3 3 5% 5% 48%	1800
	21st to end	Day	18% 10% 3 6% 3 3 3 3 5% 6% 42%	1800
December	1st to 10th	Day	15% 9% 2 5% 4 3 4 3 4 6% 46%	2885
	11th to 20th	Day	15% 9% 3 7% 5% 5% 4 3 5% 5% 38%	3008
	21st to end	Day	23% 13% 3 8% 5% 4 4 3 4 5% 28%	3982
January	1st to 10th	Night	19% 8% 3 6% 3 4 4 4 5% 7% 38%	4568
	11th to 20th	Night	15% 10% 4 7% 5% 4 4 3 5% 6% 37%	4471
	21st to end	Night	25% 10% 4 5% 4 3 3 3 5% 6% 32%	4546
February	1st to 10th	Night	20% 11% 3 8% 4 3 3 3 4 4 35%	2295
	11th to 20th	Night	17% 8% 3 8% 4 4 3 3 4 6% 41%	2218
	21st to end	Night	18% 9% 3 7% 5% 4 4 4 4 5% 38%	1884
March	1st to 10th	Night	24% 10% 3 6% 4 3 3 3 4 5% 36%	3733
	11th to 20th	Night	13% 7% 2 5% 4 4 3 4 4 6% 48%	3682
	21st to end	Night	14% 8% 3 7% 5% 4 4 4 5% 7% 41%	3466
April	1st to 10th	Night	13% 5% 2 5% 3 3 4 3 6% 8% 48%	1900
	11th to 20th	Night	15% 6% 2 5% 4 3 3 3 5% 7% 46%	1875
	21st to end	Night	16% 7% 2 6% 4 4 4 4 6% 7% 41%	1900
May	1st to 10th	Night	18% 7% 2 5% 3 4 4 4 6% 10% 38%	2912
	11th to 20th	Night	13% 6% 2 7% 5% 4 3 3 5% 7% 44%	2812
	21st to end	Night	8% 5% 3 7% 4 4 5% 4 7% 10% 43%	2876
June	1st to 10th	Night	9% 5% 2 6% 4 4 5% 4 6% 8% 47%	1520
	11th to 20th	Night	4 3 1 5% 3 4 5% 4 8% 9% 54%	1520
	21st to end	Night	3 2 1 4 4 4 5% 5% 8% 13% 50%	1520
July	1st to 10th	Night	9% 5% 2 5% 4 5% 5% 5% 6% 8% 47%	2530
	11th to 20th	Night	5% 4 2 5% 3 4 3 3 5% 10% 56%	2530
	21st to end	Night	7% 7% 3 9% 6% 6% 5% 5% 7% 9% 37%	2856
August	1st to 10th	Night	3 3 1 4 3 4 4 3 5% 8% 61%	3144
	11th to 20th	Night	5% 4 1 5% 4 4 4 4 6% 9% 53%	3100
	21st to end	Night	4 4 1 3 3 3 3 4 6% 8% 61%	3476
September	1st to 10th	Night	8% 5% 2 6% 3 3 3 3 4 6% 56%	1900
	11th to 20th	Night	8% 6% 2 5% 3 4 4 4 4 7% 53%	1999
	21st to end	Night	11% 4 2 4 3 4 3 3 5% 7% 54%	2090
October	1st to 10th	Night	7% 4 2 5% 4 3 3 2 4 6% 61%	2112
	11th to 20th	Night	14% 4 2 4 3 4 3 2 4 5% 55%	2280
	21st to end	Night	18% 6% 2 6% 3 3 3 3 4 5% 47%	2603
November	1st to 10th	Night	13% 5% 2 6% 2 3 3 2 4 7% 54%	2536
	11th to 20th	Night	14% 6% 2 4 4 3 3 3 4 7% 51%	2600
	21st to end	Night	17% 7% 3 5% 4 3 3 2 4 5% 49%	2600
December	1st to 10th	Night	17% 8% 2 7% 4 3 4 3 4 4 45%	4280
	11th to 20th	Night	18% 8% 2 5% 4 4 3 3 4 6% 43%	5199
	21st to end	Night	23% 11% 3 7% 4 4 4 3 4 5% 30%	6996

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	47% 5% 9% 26% 11% 2	2608
	11th to 20th	Day	45% 5% 9% 24% 16% 2	2714
	21st to end	Day	56% 4 9% 19% 10% 2	3144
February	1st to 10th	Day	48% 4 9% 24% 13% 2	1883
	11th to 20th	Day	48% 4 10% 21% 13% 5%	1858
	21st to end	Day	50% 4 9% 18% 13% 6%	1570
March	1st to 10th	Day	53% 4 6% 18% 12% 7%	3120
	11th to 20th	Day	37% 4 9% 27% 17% 5%	3306
	21st to end	Day	40% 7% 12% 22% 18% 1	4164
April	1st to 10th	Day	37% 6% 11% 26% 18% 2	2280
	11th to 20th	Day	42% 5% 9% 22% 18% 4	2254
	21st to end	Day	44% 6% 10% 25% 14% 2	2280
May	1st to 10th	Day	43% 11% 14% 20% 12% 1	4019
	11th to 20th	Day	43% 10% 10% 24% 12% 1	4085
	21st to end	Day	38% 9% 12% 19% 21% 1	4695
June	1st to 10th	Day	32% 9% 14% 22% 21% 2	2660
	11th to 20th	Day	27% 8% 14% 27% 22% 3	2660
	21st to end	Day	31% 9% 16% 23% 16% 5%	2660
July	1st to 10th	Day	36% 7% 15% 27% 12% 3	4371
	11th to 20th	Day	28% 8% 13% 37% 13% 2	4365
	21st to end	Day	48% 8% 13% 21% 9% 1	4537
August	1st to 10th	Day	24% 7% 15% 30% 23% 1	3773
	11th to 20th	Day	35% 7% 13% 26% 18% 1	3765
	21st to end	Day	24% 6% 13% 35% 20% 3	4179
September	1st to 10th	Day	34% 7% 10% 25% 20% 4	2280
	11th to 20th	Day	35% 6% 9% 24% 24% 2	2161
	21st to end	Day	34% 5% 8% 24% 25% 5%	2090
October	1st to 10th	Day	17% 3 6% 18% 45% 10%	3429
	11th to 20th	Day	24% 3 6% 25% 30% 13%	3140
	21st to end	Day	30% 3 6% 27% 29% 5%	3257
November	1st to 10th	Day	34% 4 9% 24% 24% 5%	1762
	11th to 20th	Day	38% 4 6% 22% 23% 6%	1800
	21st to end	Day	44% 3 7% 25% 17% 3	1800
December	1st to 10th	Day	41% 4 8% 29% 17% 1	2885
	11th to 20th	Day	46% 5% 9% 24% 13% 3	3005
	21st to end	Day	58% 5% 12% 17% 8% 1	3982
January	1st to 10th	Night	45% 5% 9% 28% 12% 1	4568
	11th to 20th	Night	46% 6% 9% 23% 14% 3	4471
	21st to end	Night	51% 5% 9% 22% 11% 1	4546
February	1st to 10th	Night	53% 4 8% 20% 14% 1	2295
	11th to 20th	Night	46% 4 7% 22% 17% 3	2219
	21st to end	Night	49% 5% 9% 16% 17% 4	1884
March	1st to 10th	Night	51% 5% 7% 13% 18% 6%	3733
	11th to 20th	Night	37% 6% 11% 22% 16% 8%	3682
	21st to end	Night	42% 6% 9% 27% 15% 1	3466
April	1st to 10th	Night	34% 5% 11% 26% 20% 4	1900
	11th to 20th	Night	37% 5% 10% 22% 21% 7%	1875
	21st to end	Night	41% 6% 10% 23% 18% 2	1900
May	1st to 10th	Night	41% 9% 15% 23% 11% 1	2941
	11th to 20th	Night	40% 8% 12% 24% 15% 1	2813
	21st to end	Night	32% 11% 13% 26% 16% 2	2884
June	1st to 10th	Night	32% 8% 12% 22% 22% 3	1520
	11th to 20th	Night	23% 8% 15% 26% 23% 6%	1520
	21st to end	Night	22% 9% 18% 26% 18% 7%	1520
July	1st to 10th	Night	33% 8% 14% 27% 16% 3	2490
	11th to 20th	Night	24% 6% 14% 35% 18% 4	2482
	21st to end	Night	42% 8% 14% 24% 11%	2766
August	1st to 10th	Night	20% 7% 15% 36% 21% 1	3132
	11th to 20th	Night	26% 7% 17% 28% 19% 3	3130
	21st to end	Night	20% 5% 11% 36% 25% 3	3476
September	1st to 10th	Night	29% 6% 9% 28% 22% 5%	1900
	11th to 20th	Night	31% 6% 8% 27% 24% 5%	1999
	21st to end	Night	30% 4 10% 25% 23% 7%	2090
October	1st to 10th	Night	17% 3 5% 14% 46% 14%	3528
	11th to 20th	Night	21% 3 5% 20% 40% 13%	3779
	21st to end	Night	29% 3 6% 24% 27% 11%	4276
November	1st to 10th	Night	32% 3 8% 25% 26% 6%	2536
	11th to 20th	Night	35% 3 7% 24% 23% 8%	2600
	21st to end	Night	40% 3 7% 25% 22% 3	2600
December	1st to 10th	Night	43% 4 8% 25% 19% 1	4280
	11th to 20th	Night	43% 4 10% 23% 19% 2	5201
	21st to end	Night	55% 6% 9% 20% 9% 2	6996

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	27% 14% 33% 20% 5% 1	300
	11th to 20th	Day	27% 19% 32% 19% 3 1	300
	21st to end	Day	21% 14% 43% 17% 5%	300
February	1st to 10th	Day	27% 12% 34% 20% 5% 1	270
	11th to 20th	Day	26% 18% 36% 17% 3 1	270
	21st to end	Day	28% 15% 34% 17% 5%	225
March	1st to 10th	Day	21% 11% 41% 20% 6% 1	270
	11th to 20th	Day	23% 15% 37% 19% 4 1	270
	21st to end	Day	23% 16% 31% 21% 8% 1	505
April	1st to 10th	Day	18% 13% 31% 27% 11% 1	460
	11th to 20th	Day	19% 13% 28% 26% 13% 2	452
	21st to end	Day	19% 9% 32% 27% 9% 4	460
May	1st to 10th	Day	16% 13% 26% 28% 13% 4	463
	11th to 20th	Day	19% 7% 18% 28% 20% 9%	487
	21st to end	Day	12% 2 21% 29% 23% 13%	644
June	1st to 10th	Day	11% 5% 15% 27% 26% 16%	680
	11th to 20th	Day	6% 1 16% 34% 31% 12%	680
	21st to end	Day	7% 2 16% 35% 25% 15%	680
July	1st to 10th	Day	9% 3 10% 27% 26% 25%	671
	11th to 20th	Day	6% 3 10% 26% 37% 18%	668
	21st to end	Day	6% 3 12% 28% 32% 19%	730
August	1st to 10th	Day	9% 2 10% 27% 32% 20%	486
	11th to 20th	Day	11% 3 12% 25% 34% 15%	479
	21st to end	Day	9% 1 7% 22% 35% 25%	539
September	1st to 10th	Day	9% 4 11% 22% 35% 20%	490
	11th to 20th	Day	11% 2 8% 24% 34% 21%	490
	21st to end	Day	15% 5% 17% 24% 25% 13%	490
October	1st to 10th	Day	9% 3 15% 35% 29% 9%	465
	11th to 20th	Day	14% 8% 32% 25% 15% 6%	300
	21st to end	Day	24% 12% 26% 25% 11% 3	330
November	1st to 10th	Day	17% 9% 27% 28% 13% 6%	300
	11th to 20th	Day	13% 13% 32% 27% 13% 2	300
	21st to end	Day	23% 14% 25% 26% 10% 2	300
December	1st to 10th	Day	20% 15% 31% 19% 12% 2	300
	11th to 20th	Day	25% 14% 27% 23% 11%	300
	21st to end	Day	28% 14% 34% 20% 3 1	330
January	1st to 10th	Night	24% 11% 31% 29% 6%	1000
	11th to 20th	Night	24% 13% 35% 22% 5%	1000
	21st to end	Night	22% 8% 39% 30% 2	1051
February	1st to 10th	Night	25% 9% 34% 28% 3	775
	11th to 20th	Night	22% 11% 39% 25% 3	743
	21st to end	Night	23% 14% 36% 25% 2	628
March	1st to 10th	Night	22% 11% 30% 32% 5%	760
	11th to 20th	Night	21% 8% 35% 28% 7%	694
	21st to end	Night	21% 10% 28% 33% 8%	627
April	1st to 10th	Night	14% 9% 35% 33% 9% 1	570
	11th to 20th	Night	17% 9% 28% 32% 13% 1	563
	21st to end	Night	19% 5% 31% 33% 11% 1	570
May	1st to 10th	Night	17% 5% 27% 34% 15% 2	570
	11th to 20th	Night	15% 5% 17% 39% 23% 2	561
	21st to end	Night	7% 2 15% 41% 30% 4	617
June	1st to 10th	Night	11% 3 14% 38% 32% 4	570
	11th to 20th	Night	5% 1 10% 44% 38% 2	570
	21st to end	Night	4 2 12% 42% 35% 5%	570
July	1st to 10th	Night	8% 1 7% 29% 43% 11%	555
	11th to 20th	Night	7% 3 8% 29% 45% 9%	552
	21st to end	Night	7% 1 11% 32% 41% 9%	624
August	1st to 10th	Night	7% 2 7% 31% 46% 8%	567
	11th to 20th	Night	8% 2 10% 33% 42% 6%	564
	21st to end	Night	8% 1 5% 30% 47% 9%	627
September	1st to 10th	Night	10% 1 9% 33% 40% 6%	570
	11th to 20th	Night	10% 1 8% 32% 41% 7%	669
	21st to end	Night	12% 3 15% 35% 29% 5%	760
October	1st to 10th	Night	9% 3 18% 35% 30% 5%	760
	11th to 20th	Night	15% 5% 25% 34% 19% 2	760
	21st to end	Night	21% 7% 26% 31% 12% 1	836
November	1st to 10th	Night	14% 7% 26% 37% 15% 1	780
	11th to 20th	Night	16% 8% 33% 31% 13%	800
	21st to end	Night	20% 9% 28% 30% 11% 1	800
December	1st to 10th	Night	24% 10% 29% 30% 7% 1	817
	11th to 20th	Night	23% 7% 30% 33% 8%	1000
	21st to end	Night	28% 10% 30% 28% 4	1100

Page generated at 2025-01-19 02:06:45. Version ac07

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