Riverview Farm Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Riverview Farm Park clear sky chart from 2005-11-06 to 2024-12-09.

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% 6% 2 6% 4 4 4 4 6% 8% 42%	101325
	Night	14% 7% 2 6% 4 4 4 3 5% 7% 43%	98408
Transparency	Day	38% 7% 13% 22% 17% 3	104961
	Night	39% 7% 11% 22% 18% 4	102911
Seeing	Day	17% 11% 27% 25% 15% 5%	15337
	Night	17% 9% 29% 30% 13% 2	24953

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	17% 6% 2 4 3 2 3 3 4 4 52%	2680
	11th to 20th	Day	13% 7% 3 6% 4 4 4 3 5% 7% 47%	2840
	21st to end	Day	13% 9% 4 8% 4 4 3 3 5% 5% 41%	3124
February	1st to 10th	Day	13% 9% 3 5% 4 6% 4 4 6% 7% 40%	1710
	11th to 20th	Day	20% 6% 2 4 2 3 4 3 4 6% 46%	1796
	21st to end	Day	16% 8% 2 6% 3 5% 5% 5% 6% 7% 37%	1570
March	1st to 10th	Day	21% 9% 4 7% 4 3 4 3 4 6% 36%	3336
	11th to 20th	Day	10% 5% 2 4 3 4 3 3 4 7% 55%	3480
	21st to end	Day	18% 8% 2 5% 4 4 4 3 5% 6% 43%	3925
April	1st to 10th	Day	12% 5% 2 5% 4 4 4 3 5% 6% 51%	2280
	11th to 20th	Day	9% 5% 2 6% 5% 3 4 5% 5% 7% 49%	2254
	21st to end	Day	14% 6% 2 6% 4 4 4 3 6% 7% 44%	2280
May	1st to 10th	Day	13% 8% 3 8% 5% 5% 5% 4 6% 10% 33%	3787
	11th to 20th	Day	18% 8% 3 7% 5% 5% 5% 4 5% 8% 33%	4225
	21st to end	Day	9% 5% 2 5% 3 4 4 5% 7% 10% 48%	4823
June	1st to 10th	Day	10% 4 2 5% 4 5% 5% 6% 7% 10% 42%	2660
	11th to 20th	Day	10% 5% 2 5% 4 5% 4 5% 8% 10% 43%	2660
	21st to end	Day	6% 4 2 6% 5% 5% 6% 5% 8% 12% 41%	2660
July	1st to 10th	Day	6% 4 2 5% 5% 5% 6% 6% 8% 13% 41%	4440
	11th to 20th	Day	12% 7% 2 7% 5% 5% 5% 5% 7% 11% 35%	4192
	21st to end	Day	8% 7% 3 8% 5% 6% 7% 6% 9% 10% 32%	4466
August	1st to 10th	Day	14% 8% 3 8% 5% 5% 7% 5% 8% 10% 27%	4090
	11th to 20th	Day	9% 6% 2 7% 5% 6% 6% 5% 7% 10% 36%	3730
	21st to end	Day	8% 4 2 5% 3 4 5% 4 7% 11% 46%	4180
September	1st to 10th	Day	14% 5% 2 5% 4 4 5% 4 7% 9% 41%	2280
	11th to 20th	Day	14% 6% 3 7% 4 4 5% 4 5% 6% 42%	2280
	21st to end	Day	20% 7% 3 6% 4 5% 4 3 5% 7% 36%	2029
October	1st to 10th	Day	16% 6% 2 6% 4 3 3 3 5% 6% 46%	1900
	11th to 20th	Day	13% 6% 2 5% 3 3 3 2 4 5% 52%	1900
	21st to end	Day	12% 4 3 6% 3 3 4 3 4 6% 52%	2090
November	1st to 10th	Day	14% 5% 1 5% 4 3 4 3 5% 7% 50%	1872
	11th to 20th	Day	14% 6% 2 5% 3 2 3 3 5% 7% 50%	1800
	21st to end	Day	14% 4 2 4 3 3 3 4 4 6% 51%	1720
December	1st to 10th	Day	16% 6% 2 5% 4 4 3 4 5% 6% 45%	1584
	11th to 20th	Day	15% 6% 2 4 3 3 3 3 4 4 53%	1910
	21st to end	Day	15% 7% 2 5% 4 4 4 3 6% 6% 44%	2772
January	1st to 10th	Night	13% 7% 2 7% 4 3 4 3 4 6% 47%	4264
	11th to 20th	Night	15% 8% 3 6% 4 3 4 3 5% 5% 43%	4120
	21st to end	Night	17% 8% 2 7% 4 3 3 2 5% 5% 43%	4532
February	1st to 10th	Night	16% 7% 2 6% 4 4 4 3 6% 6% 42%	2470
	11th to 20th	Night	20% 7% 3 6% 4 3 3 3 5% 6% 41%	2269
	21st to end	Night	17% 8% 2 6% 3 4 3 2 4 6% 46%	1884
March	1st to 10th	Night	23% 9% 3 7% 4 4 3 3 5% 5% 34%	3513
	11th to 20th	Night	14% 6% 2 5% 4 3 4 3 4 6% 50%	3480
	21st to end	Night	17% 8% 3 6% 4 3 3 2 3 4 47%	3705
April	1st to 10th	Night	12% 7% 2 6% 5% 4 4 4 6% 7% 42%	1900
	11th to 20th	Night	13% 5% 2 5% 3 3 3 3 5% 7% 50%	1875
	21st to end	Night	14% 7% 2 5% 4 3 4 4 6% 7% 45%	1900
May	1st to 10th	Night	15% 9% 3 8% 6% 5% 5% 4 6% 8% 32%	3130
	11th to 20th	Night	19% 8% 2 7% 5% 4 4 4 6% 7% 33%	2673
	21st to end	Night	10% 5% 2 6% 5% 4 4 4 5% 9% 44%	2732
June	1st to 10th	Night	11% 5% 2 4 5% 6% 4 5% 7% 10% 40%	1520
	11th to 20th	Night	8% 6% 2 6% 4 5% 6% 4 8% 9% 42%	1520
	21st to end	Night	7% 6% 2 6% 7% 5% 5% 5% 6% 8% 43%	1520
July	1st to 10th	Night	8% 4 2 6% 6% 6% 5% 4 9% 12% 38%	2520
	11th to 20th	Night	10% 7% 2 7% 5% 5% 5% 5% 8% 10% 36%	2764
	21st to end	Night	13% 9% 3 9% 6% 5% 5% 5% 7% 8% 30%	3087
August	1st to 10th	Night	17% 8% 3 7% 4 5% 5% 5% 7% 10% 29%	2825
	11th to 20th	Night	9% 6% 3 8% 5% 5% 5% 4 6% 8% 41%	3067
	21st to end	Night	9% 4 2 5% 4 5% 5% 3 7% 10% 46%	3476
September	1st to 10th	Night	12% 4 2 5% 4 4 4 4 7% 9% 45%	1900
	11th to 20th	Night	12% 7% 3 7% 4 4 4 4 4 7% 44%	1900
	21st to end	Night	18% 8% 3 7% 4 5% 4 3 4 7% 36%	2147
October	1st to 10th	Night	15% 6% 2 5% 4 4 3 3 4 6% 47%	2280
	11th to 20th	Night	14% 6% 2 5% 3 3 3 3 5% 6% 51%	2280
	21st to end	Night	13% 5% 2 4 4 3 3 3 5% 6% 52%	2508
November	1st to 10th	Night	14% 6% 2 6% 3 3 4 3 4 5% 50%	2424
	11th to 20th	Night	15% 6% 2 5% 3 3 3 3 5% 6% 48%	2600
	21st to end	Night	11% 5% 1 6% 4 3 4 3 6% 6% 51%	2675
December	1st to 10th	Night	17% 7% 3 7% 4 4 4 3 5% 5% 42%	2779
	11th to 20th	Night	17% 6% 2 5% 3 3 4 3 5% 6% 47%	3285
	21st to end	Night	14% 7% 2 6% 4 4 4 4 5% 6% 44%	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	35% 5% 6% 30% 21% 3	2681
	11th to 20th	Day	37% 5% 8% 19% 26% 5%	2840
	21st to end	Day	44% 6% 10% 20% 18% 3	3124
February	1st to 10th	Day	41% 5% 11% 25% 14% 3	1710
	11th to 20th	Day	41% 5% 9% 20% 20% 6%	1805
	21st to end	Day	44% 6% 12% 16% 17% 5%	1570
March	1st to 10th	Day	48% 6% 10% 16% 15% 5%	3336
	11th to 20th	Day	30% 6% 9% 22% 24% 8%	3480
	21st to end	Day	41% 8% 13% 18% 18% 3	3925
April	1st to 10th	Day	33% 6% 11% 22% 22% 6%	2280
	11th to 20th	Day	32% 7% 12% 24% 20% 6%	2254
	21st to end	Day	38% 7% 12% 22% 17% 5%	2280
May	1st to 10th	Day	44% 11% 15% 19% 9% 2	3822
	11th to 20th	Day	47% 10% 12% 22% 8% 1	4229
	21st to end	Day	29% 10% 17% 25% 17% 2	4837
June	1st to 10th	Day	34% 11% 15% 24% 15% 1	2660
	11th to 20th	Day	33% 10% 17% 24% 14% 2	2660
	21st to end	Day	34% 10% 17% 23% 14% 1	2660
July	1st to 10th	Day	33% 12% 21% 20% 11% 3	4370
	11th to 20th	Day	43% 10% 23% 18% 5% 1	4120
	21st to end	Day	45% 10% 15% 16% 13% 1	4324
August	1st to 10th	Day	52% 8% 17% 18% 4	4077
	11th to 20th	Day	41% 8% 14% 24% 12%	3766
	21st to end	Day	32% 9% 14% 27% 16% 2	4180
September	1st to 10th	Day	38% 10% 16% 16% 17% 4	2280
	11th to 20th	Day	43% 6% 11% 21% 17% 2	2280
	21st to end	Day	47% 7% 9% 20% 15% 2	2029
October	1st to 10th	Day	32% 5% 9% 25% 25% 4	3160
	11th to 20th	Day	25% 4 6% 19% 38% 8%	3140
	21st to end	Day	23% 3 8% 28% 26% 12%	3428
November	1st to 10th	Day	35% 5% 10% 26% 21% 4	1872
	11th to 20th	Day	35% 4 12% 22% 22% 6%	1800
	21st to end	Day	35% 4 8% 26% 22% 5%	1720
December	1st to 10th	Day	39% 5% 12% 22% 18% 4	1584
	11th to 20th	Day	35% 4 8% 28% 17% 7%	1906
	21st to end	Day	40% 5% 11% 27% 16% 2	2772
January	1st to 10th	Night	37% 5% 8% 24% 20% 5%	4264
	11th to 20th	Night	43% 6% 7% 20% 21% 3	4120
	21st to end	Night	44% 5% 7% 19% 19% 6%	4532
February	1st to 10th	Night	41% 5% 10% 23% 17% 4	2470
	11th to 20th	Night	45% 4 7% 21% 17% 6%	2271
	21st to end	Night	41% 5% 7% 22% 19% 7%	1884
March	1st to 10th	Night	51% 6% 9% 17% 14% 2	3513
	11th to 20th	Night	35% 5% 8% 19% 24% 9%	3480
	21st to end	Night	40% 5% 8% 25% 17% 5%	3705
April	1st to 10th	Night	38% 7% 11% 17% 22% 5%	1900
	11th to 20th	Night	34% 5% 11% 23% 21% 6%	1875
	21st to end	Night	37% 6% 12% 24% 17% 3	1900
May	1st to 10th	Night	46% 11% 14% 19% 10% 1	3160
	11th to 20th	Night	45% 11% 12% 23% 7% 1	2674
	21st to end	Night	33% 11% 17% 24% 13% 1	2739
June	1st to 10th	Night	34% 10% 18% 24% 14% 1	1520
	11th to 20th	Night	35% 10% 18% 22% 14% 1	1520
	21st to end	Night	34% 11% 15% 23% 15% 2	1520
July	1st to 10th	Night	38% 13% 17% 21% 9% 2	2480
	11th to 20th	Night	40% 10% 23% 21% 5% 1	2713
	21st to end	Night	50% 10% 12% 16% 12%	2988
August	1st to 10th	Night	49% 8% 19% 19% 4	2814
	11th to 20th	Night	40% 7% 18% 22% 13%	3097
	21st to end	Night	32% 7% 12% 26% 21% 1	3476
September	1st to 10th	Night	35% 8% 17% 19% 16% 4	1900
	11th to 20th	Night	40% 6% 11% 20% 20% 3	1900
	21st to end	Night	47% 7% 10% 17% 16% 2	2147
October	1st to 10th	Night	38% 5% 9% 22% 24% 3	3800
	11th to 20th	Night	26% 4 6% 20% 34% 10%	3779
	21st to end	Night	21% 4 7% 31% 25% 12%	4120
November	1st to 10th	Night	37% 5% 10% 22% 23% 4	2424
	11th to 20th	Night	37% 5% 9% 20% 20% 9%	2600
	21st to end	Night	34% 5% 9% 25% 22% 4	2675
December	1st to 10th	Night	44% 6% 9% 21% 17% 3	2779
	11th to 20th	Night	38% 5% 11% 21% 20% 6%	3288
	21st to end	Night	38% 6% 13% 23% 18% 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	22% 24% 37% 10% 7%	227
	11th to 20th	Day	26% 25% 34% 13% 2	270
	21st to end	Day	21% 24% 37% 15% 2	297
February	1st to 10th	Day	19% 22% 41% 12% 5%	270
	11th to 20th	Day	28% 26% 31% 13% 2	404
	21st to end	Day	23% 23% 36% 15% 3	382
March	1st to 10th	Day	20% 21% 39% 15% 5%	460
	11th to 20th	Day	23% 23% 32% 17% 4 1	460
	21st to end	Day	21% 20% 37% 16% 5% 1	506
April	1st to 10th	Day	20% 18% 40% 14% 6% 1	460
	11th to 20th	Day	14% 17% 38% 18% 10% 3	452
	21st to end	Day	18% 15% 35% 24% 7% 2	460
May	1st to 10th	Day	15% 18% 35% 20% 11% 1	463
	11th to 20th	Day	19% 9% 32% 28% 11% 1	487
	21st to end	Day	18% 6% 25% 28% 20% 4	529
June	1st to 10th	Day	13% 3 24% 33% 21% 5%	490
	11th to 20th	Day	12% 7% 20% 33% 21% 8%	490
	21st to end	Day	9% 4 21% 36% 23% 7%	490
July	1st to 10th	Day	9% 2 14% 36% 29% 9%	485
	11th to 20th	Day	7% 2 12% 37% 32% 9%	484
	21st to end	Day	9% 2 18% 37% 27% 7%	532
August	1st to 10th	Day	13% 2 18% 34% 24% 8%	486
	11th to 20th	Day	12% 4 13% 33% 28% 10%	479
	21st to end	Day	12% 4 14% 30% 29% 12%	539
September	1st to 10th	Day	14% 2 21% 29% 19% 14%	490
	11th to 20th	Day	17% 4 18% 30% 20% 11%	490
	21st to end	Day	25% 8% 23% 25% 14% 4	490
October	1st to 10th	Day	21% 6% 20% 25% 20% 9%	490
	11th to 20th	Day	14% 11% 28% 25% 18% 3	490
	21st to end	Day	14% 11% 32% 24% 13% 6%	539
November	1st to 10th	Day	19% 10% 29% 25% 15% 4	452
	11th to 20th	Day	19% 16% 31% 23% 10% 1	400
	21st to end	Day	18% 17% 28% 23% 13% 2	320
December	1st to 10th	Day	19% 18% 40% 16% 5% 1	196
	11th to 20th	Day	19% 13% 38% 22% 7%	180
	21st to end	Day	23% 20% 28% 19% 9% 1	198
January	1st to 10th	Night	18% 19% 36% 23% 4	760
	11th to 20th	Night	21% 15% 36% 24% 5%	760
	21st to end	Night	20% 14% 39% 25% 2	836
February	1st to 10th	Night	19% 13% 42% 23% 3	760
	11th to 20th	Night	24% 19% 39% 16% 1	743
	21st to end	Night	20% 19% 38% 21% 3	628
March	1st to 10th	Night	18% 15% 37% 25% 5%	760
	11th to 20th	Night	21% 15% 38% 21% 5%	760
	21st to end	Night	20% 14% 38% 23% 5%	836
April	1st to 10th	Night	18% 16% 41% 21% 4	760
	11th to 20th	Night	15% 12% 40% 23% 9% 1	751
	21st to end	Night	17% 10% 37% 31% 6%	760
May	1st to 10th	Night	16% 12% 36% 30% 5% 1	760
	11th to 20th	Night	15% 5% 30% 39% 9% 1	487
	21st to end	Night	14% 4 18% 44% 18% 1	411
June	1st to 10th	Night	12% 3 22% 44% 17% 2	380
	11th to 20th	Night	9% 3 22% 41% 23% 2	380
	21st to end	Night	7% 2 21% 46% 23% 1	380
July	1st to 10th	Night	9% 2 17% 46% 24% 2	370
	11th to 20th	Night	8% 2 11% 42% 33% 4	505
	21st to end	Night	10% 2 17% 45% 24% 2	624
August	1st to 10th	Night	10% 2 14% 43% 28% 3	567
	11th to 20th	Night	12% 2 13% 42% 26% 4	732
	21st to end	Night	12% 3 12% 35% 32% 6%	836
September	1st to 10th	Night	14% 3 14% 37% 25% 6%	760
	11th to 20th	Night	17% 3 15% 34% 26% 5%	760
	21st to end	Night	23% 5% 19% 31% 20% 2	760
October	1st to 10th	Night	18% 5% 18% 32% 23% 5%	760
	11th to 20th	Night	19% 8% 26% 29% 16% 2	760
	21st to end	Night	15% 8% 28% 29% 17% 3	836
November	1st to 10th	Night	18% 7% 28% 28% 16% 3	780
	11th to 20th	Night	17% 11% 32% 30% 10% 1	800
	21st to end	Night	15% 12% 30% 31% 12% 1	800
December	1st to 10th	Night	20% 12% 35% 25% 8% 1	795
	11th to 20th	Night	19% 10% 37% 28% 6%	760
	21st to end	Night	18% 12% 33% 30% 6%	836

Page generated at 2024-12-06 03:54:50. Version ac07

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